Deployment Guide
================
-----------------------
Hardware Considerations
-----------------------
Swift is designed to run on commodity hardware. At Rackspace, our storage
servers are currently running fairly generic 4U servers with 24 2T SATA
drives and 8 cores of processing power. RAID on the storage drives is not
required and not recommended. Swift's disk usage pattern is the worst
case possible for RAID, and performance degrades very quickly using RAID 5
or 6.
------------------
Deployment Options
------------------
The Swift services run completely autonomously, which provides for a lot of
flexibility when architecting the hardware deployment for Swift. The 4 main
services are:
#. Proxy Services
#. Object Services
#. Container Services
#. Account Services
The Proxy Services are more CPU and network I/O intensive. If you are using
10g networking to the proxy, or are terminating SSL traffic at the proxy,
greater CPU power will be required.
The Object, Container, and Account Services (Storage Services) are more disk
and network I/O intensive.
The easiest deployment is to install all services on each server. There is
nothing wrong with doing this, as it scales each service out horizontally.
At Rackspace, we put the Proxy Services on their own servers and all of the
Storage Services on the same server. This allows us to send 10g networking to
the proxy and 1g to the storage servers, and keep load balancing to the
proxies more manageable. Storage Services scale out horizontally as storage
servers are added, and we can scale overall API throughput by adding more
Proxies.
If you need more throughput to either Account or Container Services, they may
each be deployed to their own servers. For example you might use faster (but
more expensive) SAS or even SSD drives to get faster disk I/O to the databases.
A high-availability (HA) deployment of Swift requires that multiple proxy
servers are deployed and requests are load-balanced between them. Each proxy
server instance is stateless and able to respond to requests for the entire
cluster.
Load balancing and network design is left as an exercise to the reader,
but this is a very important part of the cluster, so time should be spent
designing the network for a Swift cluster.
---------------------
Web Front End Options
---------------------
Swift comes with an integral web front end. However, it can also be deployed
as a request processor of an Apache2 using mod_wsgi as described in
:doc:`Apache Deployment Guide <apache_deployment_guide>`.
.. _ring-preparing:
------------------
Preparing the Ring
------------------
The first step is to determine the number of partitions that will be in the
ring. We recommend that there be a minimum of 100 partitions per drive to
insure even distribution across the drives. A good starting point might be
to figure out the maximum number of drives the cluster will contain, and then
multiply by 100, and then round up to the nearest power of two.
For example, imagine we are building a cluster that will have no more than
5,000 drives. That would mean that we would have a total number of 500,000
partitions, which is pretty close to 2^19, rounded up.
It is also a good idea to keep the number of partitions small (relatively).
The more partitions there are, the more work that has to be done by the
replicators and other backend jobs and the more memory the rings consume in
process. The goal is to find a good balance between small rings and maximum
cluster size.
The next step is to determine the number of replicas to store of the data.
Currently it is recommended to use 3 (as this is the only value that has
been tested). The higher the number, the more storage that is used but the
less likely you are to lose data.
It is also important to determine how many zones the cluster should have. It is
recommended to start with a minimum of 5 zones. You can start with fewer, but
our testing has shown that having at least five zones is optimal when failures
occur. We also recommend trying to configure the zones at as high a level as
possible to create as much isolation as possible. Some example things to take
into consideration can include physical location, power availability, and
network connectivity. For example, in a small cluster you might decide to
split the zones up by cabinet, with each cabinet having its own power and
network connectivity. The zone concept is very abstract, so feel free to use
it in whatever way best isolates your data from failure. Each zone exists
in a region.
A region is also an abstract concept that may be used to distinguish between
geographically separated areas as well as can be used within same datacenter.
Regions and zones are referenced by a positive integer.
You can now start building the ring with::
swift-ring-builder <builder_file> create <part_power> <replicas> <min_part_hours>
This will start the ring build process creating the <builder_file> with
2^<part_power> partitions. <min_part_hours> is the time in hours before a
specific partition can be moved in succession (24 is a good value for this).
Devices can be added to the ring with::
swift-ring-builder <builder_file> add r<region>z<zone>-<ip>:<port>/<device_name>_<meta> <weight>
This will add a device to the ring where <builder_file> is the name of the
builder file that was created previously, <region> is the number of the region
the zone is in, <zone> is the number of the zone this device is in, <ip> is
the ip address of the server the device is in, <port> is the port number that
the server is running on, <device_name> is the name of the device on the server
(for example: sdb1), <meta> is a string of metadata for the device (optional),
and <weight> is a float weight that determines how many partitions are put on
the device relative to the rest of the devices in the cluster (a good starting
point is 100.0 x TB on the drive).Add each device that will be initially in the
cluster.
Once all of the devices are added to the ring, run::
swift-ring-builder <builder_file> rebalance
This will distribute the partitions across the drives in the ring. It is
important whenever making changes to the ring to make all the changes
required before running rebalance. This will ensure that the ring stays as
balanced as possible, and as few partitions are moved as possible.
The above process should be done to make a ring for each storage service
(Account, Container and Object). The builder files will be needed in future
changes to the ring, so it is very important that these be kept and backed up.
The resulting .tar.gz ring file should be pushed to all of the servers in the
cluster. For more information about building rings, running
swift-ring-builder with no options will display help text with available
commands and options. More information on how the ring works internally
can be found in the :doc:`Ring Overview <overview_ring>`.
.. _server-per-port-configuration:
-------------------------------
Running object-servers Per Disk
-------------------------------
The lack of true asynchronous file I/O on Linux leaves the object-server
workers vulnerable to misbehaving disks. Because any object-server worker can
service a request for any disk, and a slow I/O request blocks the eventlet hub,
a single slow disk can impair an entire storage node. This also prevents
object servers from fully utilizing all their disks during heavy load.
Another way to get full I/O isolation is to give each disk on a storage node a
different port in the storage policy rings. Then set the
:ref:`servers_per_port <object-server-default-options>`
option in the object-server config. NOTE: while the purpose of this config
setting is to run one or more object-server worker processes per *disk*, the
implementation just runs object-servers per unique port of local devices in the
rings. The deployer must combine this option with appropriately-configured
rings to benefit from this feature.
Here's an example (abbreviated) old-style ring (2 node cluster with 2 disks
each)::
Devices: id region zone ip address port replication ip replication port name
0 1 1 1.1.0.1 6200 1.1.0.1 6200 d1
1 1 1 1.1.0.1 6200 1.1.0.1 6200 d2
2 1 2 1.1.0.2 6200 1.1.0.2 6200 d3
3 1 2 1.1.0.2 6200 1.1.0.2 6200 d4
And here's the same ring set up for `servers_per_port`::
Devices: id region zone ip address port replication ip replication port name
0 1 1 1.1.0.1 6200 1.1.0.1 6200 d1
1 1 1 1.1.0.1 6201 1.1.0.1 6201 d2
2 1 2 1.1.0.2 6200 1.1.0.2 6200 d3
3 1 2 1.1.0.2 6201 1.1.0.2 6201 d4
When migrating from normal to `servers_per_port`, perform these steps in order:
#. Upgrade Swift code to a version capable of doing `servers_per_port`.
#. Enable `servers_per_port` with a > 0 value
#. Restart `swift-object-server` processes with a SIGHUP. At this point, you
will have the `servers_per_port` number of `swift-object-server` processes
serving all requests for all disks on each node. This preserves
availability, but you should perform the next step as quickly as possible.
#. Push out new rings that actually have different ports per disk on each
server. One of the ports in the new ring should be the same as the port
used in the old ring ("6200" in the example above). This will cover
existing proxy-server processes who haven't loaded the new ring yet. They
can still talk to any storage node regardless of whether or not that
storage node has loaded the ring and started object-server processes on the
new ports.
If you do not run a separate object-server for replication, then this setting
must be available to the object-replicator and object-reconstructor (i.e.
appear in the [DEFAULT] config section).
.. _general-service-configuration:
-----------------------------
General Service Configuration
-----------------------------
Most Swift services fall into two categories. Swift's wsgi servers and
background daemons.
For more information specific to the configuration of Swift's wsgi servers
with paste deploy see :ref:`general-server-configuration`.
Configuration for servers and daemons can be expressed together in the same
file for each type of server, or separately. If a required section for the
service trying to start is missing there will be an error. The sections not
used by the service are ignored.
Consider the example of an object storage node. By convention, configuration
for the object-server, object-updater, object-replicator, object-auditor, and
object-reconstructor exist in a single file ``/etc/swift/object-server.conf``::
[DEFAULT]
reclaim_age = 604800
[pipeline:main]
pipeline = object-server
[app:object-server]
use = egg:swift#object
[object-replicator]
[object-updater]
[object-auditor]
Swift services expect a configuration path as the first argument::
$ swift-object-auditor
Usage: swift-object-auditor CONFIG [options]
Error: missing config path argument
If you omit the object-auditor section this file could not be used as the
configuration path when starting the ``swift-object-auditor`` daemon::
$ swift-object-auditor /etc/swift/object-server.conf
Unable to find object-auditor config section in /etc/swift/object-server.conf
If the configuration path is a directory instead of a file all of the files in
the directory with the file extension ".conf" will be combined to generate the
configuration object which is delivered to the Swift service. This is
referred to generally as "directory based configuration".
Directory based configuration leverages ConfigParser's native multi-file
support. Files ending in ".conf" in the given directory are parsed in
lexicographical order. Filenames starting with '.' are ignored. A mixture of
file and directory configuration paths is not supported - if the configuration
path is a file only that file will be parsed.
The Swift service management tool ``swift-init`` has adopted the convention of
looking for ``/etc/swift/{type}-server.conf.d/`` if the file
``/etc/swift/{type}-server.conf`` file does not exist.
When using directory based configuration, if the same option under the same
section appears more than once in different files, the last value parsed is
said to override previous occurrences. You can ensure proper override
precedence by prefixing the files in the configuration directory with
numerical values.::
/etc/swift/
default.base
object-server.conf.d/
000_default.conf -> ../default.base
001_default-override.conf
010_server.conf
020_replicator.conf
030_updater.conf
040_auditor.conf
You can inspect the resulting combined configuration object using the
``swift-config`` command line tool
.. _general-server-configuration:
----------------------------
General Server Configuration
----------------------------
Swift uses paste.deploy (http://pythonpaste.org/deploy/) to manage server
configurations.
Default configuration options are set in the `[DEFAULT]` section, and any
options specified there can be overridden in any of the other sections BUT
ONLY BY USING THE SYNTAX ``set option_name = value``. This is the unfortunate
way paste.deploy works and I'll try to explain it in full.
First, here's an example paste.deploy configuration file::
[DEFAULT]
name1 = globalvalue
name2 = globalvalue
name3 = globalvalue
set name4 = globalvalue
[pipeline:main]
pipeline = myapp
[app:myapp]
use = egg:mypkg#myapp
name2 = localvalue
set name3 = localvalue
set name5 = localvalue
name6 = localvalue
The resulting configuration that myapp receives is::
global {'__file__': '/etc/mypkg/wsgi.conf', 'here': '/etc/mypkg',
'name1': 'globalvalue',
'name2': 'globalvalue',
'name3': 'localvalue',
'name4': 'globalvalue',
'name5': 'localvalue',
'set name4': 'globalvalue'}
local {'name6': 'localvalue'}
So, `name1` got the global value which is fine since it's only in the `DEFAULT`
section anyway.
`name2` got the global value from `DEFAULT` even though it appears to be
overridden in the `app:myapp` subsection. This is just the unfortunate way
paste.deploy works (at least at the time of this writing.)
`name3` got the local value from the `app:myapp` subsection because it is using
the special paste.deploy syntax of ``set option_name = value``. So, if you want
a default value for most app/filters but want to override it in one
subsection, this is how you do it.
`name4` got the global value from `DEFAULT` since it's only in that section
anyway. But, since we used the ``set`` syntax in the `DEFAULT` section even
though we shouldn't, notice we also got a ``set name4`` variable. Weird, but
probably not harmful.
`name5` got the local value from the `app:myapp` subsection since it's only
there anyway, but notice that it is in the global configuration and not the
local configuration. This is because we used the ``set`` syntax to set the
value. Again, weird, but not harmful since Swift just treats the two sets of
configuration values as one set anyway.
`name6` got the local value from `app:myapp` subsection since it's only there,
and since we didn't use the ``set`` syntax, it's only in the local
configuration and not the global one. Though, as indicated above, there is no
special distinction with Swift.
That's quite an explanation for something that should be so much simpler, but
it might be important to know how paste.deploy interprets configuration files.
The main rule to remember when working with Swift configuration files is:
.. note::
Use the ``set option_name = value`` syntax in subsections if the option is
also set in the ``[DEFAULT]`` section. Don't get in the habit of always
using the ``set`` syntax or you'll probably mess up your non-paste.deploy
configuration files.
--------------------
Common configuration
--------------------
An example of common configuration file can be found at etc/swift.conf-sample
The following configuration options are available:
========================== ========== =============================================
Option Default Description
-------------------------- ---------- ---------------------------------------------
max_header_size 8192 max_header_size is the max number of bytes in
the utf8 encoding of each header. Using 8192
as default because eventlet use 8192 as max
size of header line. This value may need to
be increased when using identity v3 API
tokens including more than 7 catalog entries.
See also include_service_catalog in
proxy-server.conf-sample (documented in
overview_auth.rst).
extra_header_count 0 By default the maximum number of allowed
headers depends on the number of max
allowed metadata settings plus a default
value of 32 for regular http headers.
If for some reason this is not enough (custom
middleware for example) it can be increased
with the extra_header_count constraint.
auto_create_account_prefix . Prefix used when automatically creating
accounts.
========================== ========== =============================================
---------------------------
Object Server Configuration
---------------------------
An Example Object Server configuration can be found at
etc/object-server.conf-sample in the source code repository.
The following configuration sections are available:
* :ref:`[DEFAULT] <object-server-default-options>`
* `[object-server]`_
* `[object-replicator]`_
* `[object-reconstructor]`_
* `[object-updater]`_
* `[object-auditor]`_
* `[object-expirer]`_
.. _object-server-default-options:
*********
[DEFAULT]
*********
================================ ========== ============================================
Option Default Description
-------------------------------- ---------- --------------------------------------------
swift_dir /etc/swift Swift configuration directory
devices /srv/node Parent directory of where devices are
mounted
mount_check true Whether or not check if the devices are
mounted to prevent accidentally writing
to the root device
bind_ip 0.0.0.0 IP Address for server to bind to
bind_port 6200 Port for server to bind to
keep_idle 600 Value to set for socket TCP_KEEPIDLE
bind_timeout 30 Seconds to attempt bind before giving up
backlog 4096 Maximum number of allowed pending
connections
workers auto Override the number of pre-forked workers
that will accept connections. If set it
should be an integer, zero means no fork.
If unset, it will try to default to the
number of effective cpu cores and fallback
to one. Increasing the number of workers
helps slow filesystem operations in one
request from negatively impacting other
requests, but only the
:ref:`servers_per_port
<server-per-port-configuration>` option
provides complete I/O isolation with no
measurable overhead.
servers_per_port 0 If each disk in each storage policy ring
has unique port numbers for its "ip"
value, you can use this setting to have
each object-server worker only service
requests for the single disk matching the
port in the ring. The value of this
setting determines how many worker
processes run for each port (disk) in the
ring. If you have 24 disks per server, and
this setting is 4, then each storage node
will have 1 + (24 * 4) = 97 total
object-server processes running. This
gives complete I/O isolation, drastically
reducing the impact of slow disks on
storage node performance. The
object-replicator and object-reconstructor
need to see this setting too, so it must
be in the [DEFAULT] section.
See :ref:`server-per-port-configuration`.
max_clients 1024 Maximum number of clients one worker can
process simultaneously (it will actually
accept(2) N + 1). Setting this to one (1)
will only handle one request at a time,
without accepting another request
concurrently.
disable_fallocate false Disable "fast fail" fallocate checks if
the underlying filesystem does not support
it.
log_name swift Label used when logging
log_facility LOG_LOCAL0 Syslog log facility
log_level INFO Logging level
log_address /dev/log Logging directory
log_max_line_length 0 Caps the length of log lines to the
value given; no limit if set to 0, the
default.
log_custom_handlers None Comma-separated list of functions to call
to setup custom log handlers.
log_udp_host Override log_address
log_udp_port 514 UDP log port
log_statsd_host None Enables StatsD logging; IPv4/IPv6
address or a hostname. If a
hostname resolves to an IPv4 and IPv6
address, the IPv4 address will be
used.
log_statsd_port 8125
log_statsd_default_sample_rate 1.0
log_statsd_sample_rate_factor 1.0
log_statsd_metric_prefix
eventlet_debug false If true, turn on debug logging for
eventlet
fallocate_reserve 1% You can set fallocate_reserve to the
number of bytes or percentage of disk
space you'd like fallocate to reserve,
whether there is space for the given
file size or not. Percentage will be used
if the value ends with a '%'. This is
useful for systems that behave badly when
they completely run out of space; you can
make the services pretend they're out of
space early.
conn_timeout 0.5 Time to wait while attempting to connect
to another backend node.
node_timeout 3 Time to wait while sending each chunk of
data to another backend node.
client_timeout 60 Time to wait while receiving each chunk of
data from a client or another backend node
network_chunk_size 65536 Size of chunks to read/write over the
network
disk_chunk_size 65536 Size of chunks to read/write to disk
container_update_timeout 1 Time to wait while sending a container
update on object update.
reclaim_age 604800 Time elapsed in seconds before the tombstone
file representing a deleted object can be
reclaimed. This is the maximum window for
your consistency engine. If a node that was
disconnected from the cluster because of a
fault is reintroduced into the cluster after
this window without having its data purged
it will result in dark data. This setting
should be consistent across all object
services.
nice_priority None Scheduling priority of server processes.
Niceness values range from -20 (most
favorable to the process) to 19 (least
favorable to the process). The default
does not modify priority.
ionice_class None I/O scheduling class of server processes.
I/O niceness class values are IOPRIO_CLASS_RT
(realtime), IOPRIO_CLASS_BE (best-effort),
and IOPRIO_CLASS_IDLE (idle).
The default does not modify class and
priority. Linux supports io scheduling
priorities and classes since 2.6.13 with
the CFQ io scheduler.
Work only with ionice_priority.
ionice_priority None I/O scheduling priority of server
processes. I/O niceness priority is
a number which goes from 0 to 7.
The higher the value, the lower the I/O
priority of the process. Work only with
ionice_class.
Ignored if IOPRIO_CLASS_IDLE is set.
================================ ========== ============================================
.. _object-server-options:
***************
[object-server]
***************
================================== ====================== ===============================================
Option Default Description
---------------------------------- ---------------------- -----------------------------------------------
use paste.deploy entry point for the
object server. For most cases,
this should be
`egg:swift#object`.
set log_name object-server Label used when logging
set log_facility LOG_LOCAL0 Syslog log facility
set log_level INFO Logging level
set log_requests True Whether or not to log each
request
set log_address /dev/log Logging directory
user swift User to run as
max_upload_time 86400 Maximum time allowed to upload an
object
slow 0 If > 0, Minimum time in seconds for a PUT or
DELETE request to complete. This is only
useful to simulate slow devices during testing
and development.
mb_per_sync 512 On PUT requests, sync file every
n MB
keep_cache_size 5242880 Largest object size to keep in
buffer cache
keep_cache_private false Allow non-public objects to stay
in kernel's buffer cache
allowed_headers Content-Disposition, Comma separated list of headers
Content-Encoding, that can be set in metadata on an object.
X-Delete-At, This list is in addition to
X-Object-Manifest, X-Object-Meta-* headers and cannot include
X-Static-Large-Object Content-Type, etag, Content-Length, or deleted
Cache-Control,
Content-Language,
Expires,
X-Robots-Tag
replication_server Configure parameter for creating
specific server. To handle all verbs,
including replication verbs, do not
specify "replication_server"
(this is the default). To only
handle replication, set to a True
value (e.g. "True" or "1").
To handle only non-replication
verbs, set to "False". Unless you
have a separate replication network, you
should not specify any value for
"replication_server".
replication_concurrency 4 Set to restrict the number of
concurrent incoming SSYNC
requests; set to 0 for unlimited
replication_concurrency_per_device 1 Set to restrict the number of
concurrent incoming SSYNC
requests per device; set to 0 for
unlimited requests per devices.
This can help control I/O to each
device. This does not override
replication_concurrency described
above, so you may need to adjust
both parameters depending on your
hardware or network capacity.
replication_lock_timeout 15 Number of seconds to wait for an
existing replication device lock
before giving up.
replication_failure_threshold 100 The number of subrequest failures
before the
replication_failure_ratio is
checked
replication_failure_ratio 1.0 If the value of failures /
successes of SSYNC
subrequests exceeds this ratio,
the overall SSYNC request
will be aborted
splice no Use splice() for zero-copy object
GETs. This requires Linux kernel
version 3.0 or greater. If you set
"splice = yes" but the kernel
does not support it, error messages
will appear in the object server
logs at startup, but your object
servers should continue to function.
nice_priority None Scheduling priority of server processes.
Niceness values range from -20 (most
favorable to the process) to 19 (least
favorable to the process). The default
does not modify priority.
ionice_class None I/O scheduling class of server processes.
I/O niceness class values are IOPRIO_CLASS_RT
(realtime), IOPRIO_CLASS_BE (best-effort),
and IOPRIO_CLASS_IDLE (idle).
The default does not modify class and
priority. Linux supports io scheduling
priorities and classes since 2.6.13 with
the CFQ io scheduler.
Work only with ionice_priority.
ionice_priority None I/O scheduling priority of server
processes. I/O niceness priority is
a number which goes from 0 to 7.
The higher the value, the lower the I/O
priority of the process. Work only with
ionice_class.
Ignored if IOPRIO_CLASS_IDLE is set.
eventlet_tpool_num_threads auto The number of threads in eventlet's thread pool.
Most IO will occur in the object server's main
thread, but certain "heavy" IO operations will
occur in separate IO threads, managed by
eventlet.
The default value is auto, whose actual value
is dependent on the servers_per_port value.
If servers_per_port is zero then it uses
eventlet's default (currently 20 threads).
If the servers_per_port is nonzero then it'll
only use 1 thread per process.
This value can be overridden with an integer
value.
================================== ====================== ===============================================
*******************
[object-replicator]
*******************
=========================== ======================== ================================
Option Default Description
--------------------------- ------------------------ --------------------------------
log_name object-replicator Label used when logging
log_facility LOG_LOCAL0 Syslog log facility
log_level INFO Logging level
log_address /dev/log Logging directory
daemonize yes Whether or not to run replication
as a daemon
interval 30 Time in seconds to wait between
replication passes
concurrency 1 Number of replication jobs to
run per worker process
replicator_workers 0 Number of worker processes to use.
No matter how big this number is,
at most one worker per disk will
be used. The default value of 0
means no forking; all work is done
in the main process.
sync_method rsync The sync method to use; default
is rsync but you can use ssync to
try the EXPERIMENTAL
all-swift-code-no-rsync-callouts
method. Once ssync is verified as
or better than, rsync, we plan to
deprecate rsync so we can move on
with more features for
replication.
rsync_timeout 900 Max duration of a partition rsync
rsync_bwlimit 0 Bandwidth limit for rsync in kB/s.
0 means unlimited.
rsync_io_timeout 30 Timeout value sent to rsync
--timeout and --contimeout
options
rsync_compress no Allow rsync to compress data
which is transmitted to destination
node during sync. However, this
is applicable only when destination
node is in a different region
than the local one.
NOTE: Objects that are already
compressed (for example: .tar.gz,
.mp3) might slow down the syncing
process.
stats_interval 300 Interval in seconds between
logging replication statistics
handoffs_first false If set to True, partitions that
are not supposed to be on the
node will be replicated first.
The default setting should not be
changed, except for extreme
situations.
handoff_delete auto By default handoff partitions
will be removed when it has
successfully replicated to all
the canonical nodes. If set to an
integer n, it will remove the
partition if it is successfully
replicated to n nodes. The
default setting should not be
changed, except for extreme
situations.
node_timeout DEFAULT or 10 Request timeout to external
services. This uses what's set
here, or what's set in the
DEFAULT section, or 10 (though
other sections use 3 as the final
default).
http_timeout 60 Max duration of an http request.
This is for REPLICATE finalization
calls and so should be longer
than node_timeout.
lockup_timeout 1800 Attempts to kill all workers if
nothing replicates for
lockup_timeout seconds
rsync_module {replication_ip}::object Format of the rsync module where
the replicator will send data.
The configuration value can
include some variables that will
be extracted from the ring.
Variables must follow the format
{NAME} where NAME is one of: ip,
port, replication_ip,
replication_port, region, zone,
device, meta. See
etc/rsyncd.conf-sample for some
examples.
rsync_error_log_line_length 0 Limits how long rsync error log
lines are
ring_check_interval 15 Interval for checking new ring
file
recon_cache_path /var/cache/swift Path to recon cache
nice_priority None Scheduling priority of server
processes. Niceness values
range from -20 (most favorable
to the process) to 19 (least
favorable to the process).
The default does not modify
priority.
ionice_class None I/O scheduling class of server
processes. I/O niceness class
values are IOPRIO_CLASS_RT (realtime),
IOPRIO_CLASS_BE (best-effort),
and IOPRIO_CLASS_IDLE (idle).
The default does not modify
class and priority.
Linux supports io scheduling
priorities and classes since
2.6.13 with the CFQ io scheduler.
Work only with ionice_priority.
ionice_priority None I/O scheduling priority of server
processes. I/O niceness priority
is a number which goes from
0 to 7. The higher the value,
the lower the I/O priority of
the process.
Work only with ionice_class.
Ignored if IOPRIO_CLASS_IDLE
is set.
=========================== ======================== ================================
**********************
[object-reconstructor]
**********************
=========================== ======================== ================================
Option Default Description
--------------------------- ------------------------ --------------------------------
log_name object-reconstructor Label used when logging
log_facility LOG_LOCAL0 Syslog log facility
log_level INFO Logging level
log_address /dev/log Logging directory
daemonize yes Whether or not to run
reconstruction as a daemon
interval 30 Time in seconds to wait between
reconstruction passes
reconstructor_workers 0 Maximum number of worker processes
to spawn. Each worker will handle
a subset of devices. Devices will
be assigned evenly among the workers
so that workers cycle at similar
intervals (which can lead to fewer
workers than requested). You can not
have more workers than devices. If
you have no devices only a single
worker is spawned.
concurrency 1 Number of reconstruction threads to
spawn per reconstructor process.
stats_interval 300 Interval in seconds between
logging reconstruction statistics
handoffs_only false The handoffs_only mode option is for
special case emergency situations
during rebalance such as disk full in
the cluster. This option SHOULD NOT
BE CHANGED, except for extreme
situations. When handoffs_only mode
is enabled the reconstructor will
*only* revert fragments from handoff
nodes to primary nodes and will not
sync primary nodes with neighboring
primary nodes. This will force the
reconstructor to sync and delete
handoffs' fragments more quickly and
minimize the time of the rebalance by
limiting the number of rebuilds. The
handoffs_only option is only for
temporary use and should be disabled
as soon as the emergency situation
has been resolved.
node_timeout DEFAULT or 10 Request timeout to external
services. The value used is the value
set in this section, or the value set
in the DEFAULT section, or 10.
http_timeout 60 Max duration of an http request.
This is for REPLICATE finalization
calls and so should be longer
than node_timeout.
lockup_timeout 1800 Attempts to kill all threads if
no fragment has been reconstructed
for lockup_timeout seconds.
ring_check_interval 15 Interval for checking new ring
file
recon_cache_path /var/cache/swift Path to recon cache
nice_priority None Scheduling priority of server
processes. Niceness values
range from -20 (most favorable
to the process) to 19 (least
favorable to the process).
The default does not modify
priority.
ionice_class None I/O scheduling class of server
processes. I/O niceness class
values are IOPRIO_CLASS_RT (realtime),
IOPRIO_CLASS_BE (best-effort),
and IOPRIO_CLASS_IDLE (idle).
The default does not modify
class and priority.
Linux supports io scheduling
priorities and classes since
2.6.13 with the CFQ io scheduler.
Work only with ionice_priority.
ionice_priority None I/O scheduling priority of server
processes. I/O niceness priority
is a number which goes from
0 to 7. The higher the value,
the lower the I/O priority of
the process.
Work only with ionice_class.
Ignored if IOPRIO_CLASS_IDLE
is set.
=========================== ======================== ================================
****************
[object-updater]
****************
=================== =================== ==========================================
Option Default Description
------------------- ------------------- ------------------------------------------
log_name object-updater Label used when logging
log_facility LOG_LOCAL0 Syslog log facility
log_level INFO Logging level
log_address /dev/log Logging directory
interval 300 Minimum time for a pass to take
updater_workers 1 Number of worker processes
concurrency 8 Number of updates to run concurrently in
each worker process
node_timeout DEFAULT or 10 Request timeout to external services. This
uses what's set here, or what's set in the
DEFAULT section, or 10 (though other
sections use 3 as the final default).
objects_per_second 50 Maximum objects updated per second.
Should be tuned according to individual
system specs. 0 is unlimited.
slowdown 0.01 Time in seconds to wait between objects.
Deprecated in favor of objects_per_second.
report_interval 300 Interval in seconds between logging
statistics about the current update pass.
recon_cache_path /var/cache/swift Path to recon cache
nice_priority None Scheduling priority of server processes.
Niceness values range from -20 (most
favorable to the process) to 19 (least
favorable to the process). The default
does not modify priority.
ionice_class None I/O scheduling class of server processes.
I/O niceness class values are IOPRIO_CLASS_RT
(realtime), IOPRIO_CLASS_BE (best-effort),
and IOPRIO_CLASS_IDLE (idle).
The default does not modify class and
priority. Linux supports io scheduling
priorities and classes since 2.6.13 with
the CFQ io scheduler.
Work only with ionice_priority.
ionice_priority None I/O scheduling priority of server
processes. I/O niceness priority is
a number which goes from 0 to 7.
The higher the value, the lower the I/O
priority of the process. Work only with
ionice_class.
Ignored if IOPRIO_CLASS_IDLE is set.
=================== =================== ==========================================
****************
[object-auditor]
****************
=========================== =================== ==========================================
Option Default Description
--------------------------- ------------------- ------------------------------------------
log_name object-auditor Label used when logging
log_facility LOG_LOCAL0 Syslog log facility
log_level INFO Logging level
log_address /dev/log Logging directory
log_time 3600 Frequency of status logs in seconds.
interval 30 Time in seconds to wait between
auditor passes
disk_chunk_size 65536 Size of chunks read during auditing
files_per_second 20 Maximum files audited per second per
auditor process. Should be tuned according
to individual system specs. 0 is unlimited.
bytes_per_second 10000000 Maximum bytes audited per second per
auditor process. Should be tuned according
to individual system specs. 0 is unlimited.
concurrency 1 The number of parallel processes to use
for checksum auditing.
zero_byte_files_per_second 50
object_size_stats
recon_cache_path /var/cache/swift Path to recon cache
rsync_tempfile_timeout auto Time elapsed in seconds before rsync
tempfiles will be unlinked. Config value
of "auto" try to use object-replicator's
rsync_timeout + 900 or fallback to 86400
(1 day).
nice_priority None Scheduling priority of server processes.
Niceness values range from -20 (most
favorable to the process) to 19 (least
favorable to the process). The default
does not modify priority.
ionice_class None I/O scheduling class of server processes.
I/O niceness class values are IOPRIO_CLASS_RT
(realtime), IOPRIO_CLASS_BE (best-effort),
and IOPRIO_CLASS_IDLE (idle).
The default does not modify class and
priority. Linux supports io scheduling
priorities and classes since 2.6.13 with
the CFQ io scheduler.
Work only with ionice_priority.
ionice_priority None I/O scheduling priority of server
processes. I/O niceness priority is
a number which goes from 0 to 7.
The higher the value, the lower the I/O
priority of the process. Work only with
ionice_class.
Ignored if IOPRIO_CLASS_IDLE is set.
=========================== =================== ==========================================
****************
[object-expirer]
****************
============================= =============================== ==========================================
Option Default Description
----------------------------- ------------------------------- ------------------------------------------
log_name object-expirer Label used when logging
log_facility LOG_LOCAL0 Syslog log facility
log_level INFO Logging level
log_address /dev/log Logging directory
interval 300 Time in seconds to wait between
expirer passes
report_interval 300 Frequency of status logs in seconds.
concurrency 1 Level of concurrency to use to do the work,
this value must be set to at least 1
expiring_objects_account_name expiring_objects name for legacy expirer task queue
dequeue_from_legacy False This service will look for jobs on the legacy expirer task queue.
processes 0 How many parts to divide the legacy work into,
one part per process that will be doing the work.
When set 0 means that a single legacy
process will be doing all the work.
This can only be used in conjunction with
`dequeue_from_legacy`.
process 0 Which of the parts a particular legacy process will
work on. It is "zero based", if you want to use 3
processes, you should run processes with process
set to 0, 1, and 2.
This can only be used in conjunction with
`dequeue_from_legacy`.
reclaim_age 604800 How long an un-processable expired object
marker will be retried before it is abandoned.
It is not coupled with the tombstone reclaim age
in the consistency engine.
request_tries 3 The number of times the expirer's internal client
will attempt any given request in the event
of failure
recon_cache_path /var/cache/swift Path to recon cache
nice_priority None Scheduling priority of server processes.
Niceness values range from -20 (most
favorable to the process) to 19 (least
favorable to the process). The default
does not modify priority.
ionice_class None I/O scheduling class of server processes.
I/O niceness class values are IOPRIO_CLASS_RT
(realtime), IOPRIO_CLASS_BE (best-effort),
and IOPRIO_CLASS_IDLE (idle).
The default does not modify class and
priority. Linux supports io scheduling
priorities and classes since 2.6.13 with
the CFQ io scheduler.
Work only with ionice_priority.
ionice_priority None I/O scheduling priority of server
processes. I/O niceness priority is
a number which goes from 0 to 7.
The higher the value, the lower the I/O
priority of the process. Work only with
ionice_class.
Ignored if IOPRIO_CLASS_IDLE is set.
============================= =============================== ==========================================
------------------------------
Container Server Configuration
------------------------------
An example Container Server configuration can be found at
etc/container-server.conf-sample in the source code repository.
The following configuration sections are available:
* :ref:`[DEFAULT] <container_server_default_options>`
* `[container-server]`_
* `[container-replicator]`_
* `[container-updater]`_
* `[container-auditor]`_
.. _container_server_default_options:
*********
[DEFAULT]
*********
=============================== ========== ============================================
Option Default Description
------------------------------- ---------- --------------------------------------------
swift_dir /etc/swift Swift configuration directory
devices /srv/node Parent directory of where devices are mounted
mount_check true Whether or not check if the devices are
mounted to prevent accidentally writing
to the root device
bind_ip 0.0.0.0 IP Address for server to bind to
bind_port 6201 Port for server to bind to
keep_idle 600 Value to set for socket TCP_KEEPIDLE
bind_timeout 30 Seconds to attempt bind before giving up
backlog 4096 Maximum number of allowed pending
connections
workers auto Override the number of pre-forked workers
that will accept connections. If set it
should be an integer, zero means no fork. If
unset, it will try to default to the number
of effective cpu cores and fallback to one.
Increasing the number of workers may reduce
the possibility of slow file system
operations in one request from negatively
impacting other requests. See
:ref:`general-service-tuning`.
max_clients 1024 Maximum number of clients one worker can
process simultaneously (it will actually
accept(2) N + 1). Setting this to one (1)
will only handle one request at a time,
without accepting another request
concurrently.
user swift User to run as
disable_fallocate false Disable "fast fail" fallocate checks if the
underlying filesystem does not support it.
log_name swift Label used when logging
log_facility LOG_LOCAL0 Syslog log facility
log_level INFO Logging level
log_address /dev/log Logging directory
log_max_line_length 0 Caps the length of log lines to the
value given; no limit if set to 0, the
default.
log_custom_handlers None Comma-separated list of functions to call
to setup custom log handlers.
log_udp_host Override log_address
log_udp_port 514 UDP log port
log_statsd_host None Enables StatsD logging; IPv4/IPv6
address or a hostname. If a
hostname resolves to an IPv4 and IPv6
address, the IPv4 address will be
used.
log_statsd_port 8125
log_statsd_default_sample_rate 1.0
log_statsd_sample_rate_factor 1.0
log_statsd_metric_prefix
eventlet_debug false If true, turn on debug logging for eventlet
fallocate_reserve 1% You can set fallocate_reserve to the
number of bytes or percentage of disk
space you'd like fallocate to reserve,
whether there is space for the given
file size or not. Percentage will be used
if the value ends with a '%'. This is
useful for systems that behave badly when
they completely run out of space; you can
make the services pretend they're out of
space early.
db_preallocation off If you don't mind the extra disk space usage
in overhead, you can turn this on to preallocate
disk space with SQLite databases to decrease
fragmentation.
nice_priority None Scheduling priority of server processes.
Niceness values range from -20 (most
favorable to the process) to 19 (least
favorable to the process). The default
does not modify priority.
ionice_class None I/O scheduling class of server processes.
I/O niceness class values are IOPRIO_CLASS_RT
(realtime), IOPRIO_CLASS_BE (best-effort),
and IOPRIO_CLASS_IDLE (idle).
The default does not modify class and
priority. Linux supports io scheduling
priorities and classes since 2.6.13
with the CFQ io scheduler.
Work only with ionice_priority.
ionice_priority None I/O scheduling priority of server processes.
I/O niceness priority is a number which
goes from 0 to 7. The higher the value,
the lower the I/O priority of the process.
Work only with ionice_class.
Ignored if IOPRIO_CLASS_IDLE is set.
=============================== ========== ============================================
******************
[container-server]
******************
============================== ================ ========================================
Option Default Description
------------------------------ ---------------- ----------------------------------------
use paste.deploy entry point for the
container server. For most cases, this
should be `egg:swift#container`.
set log_name container-server Label used when logging
set log_facility LOG_LOCAL0 Syslog log facility
set log_level INFO Logging level
set log_requests True Whether or not to log each
request
set log_address /dev/log Logging directory
node_timeout 3 Request timeout to external services
conn_timeout 0.5 Connection timeout to external services
allow_versions false Enable/Disable object versioning feature
replication_server Configure parameter for creating
specific server. To handle all verbs,
including replication verbs, do not
specify "replication_server"
(this is the default). To only
handle replication, set to a True
value (e.g. "True" or "1").
To handle only non-replication
verbs, set to "False". Unless you
have a separate replication network, you
should not specify any value for
"replication_server".
nice_priority None Scheduling priority of server processes.
Niceness values range from -20 (most
favorable to the process) to 19 (least
favorable to the process). The default
does not modify priority.
ionice_class None I/O scheduling class of server processes.
I/O niceness class values are
IOPRIO_CLASS_RT (realtime),
IOPRIO_CLASS_BE (best-effort),
and IOPRIO_CLASS_IDLE (idle).
The default does not modify class and
priority. Linux supports io scheduling
priorities and classes since 2.6.13 with
the CFQ io scheduler.
Work only with ionice_priority.
ionice_priority None I/O scheduling priority of server
processes. I/O niceness priority is
a number which goes from 0 to 7.
The higher the value, the lower the I/O
priority of the process. Work only with
ionice_class.
Ignored if IOPRIO_CLASS_IDLE is set.
============================== ================ ========================================
**********************
[container-replicator]
**********************
==================== =========================== =============================
Option Default Description
-------------------- --------------------------- -----------------------------
log_name container-replicator Label used when logging
log_facility LOG_LOCAL0 Syslog log facility
log_level INFO Logging level
log_address /dev/log Logging directory
per_diff 1000 Maximum number of database
rows that will be sync'd in a
single HTTP replication
request. Databases with less
than or equal to this number
of differing rows will always
be sync'd using an HTTP
replication request rather
than using rsync.
max_diffs 100 Maximum number of HTTP
replication requests attempted
on each replication pass for
any one container. This caps
how long the replicator will
spend trying to sync a given
database per pass so the other
databases don't get starved.
concurrency 8 Number of replication workers
to spawn
interval 30 Time in seconds to wait
between replication passes
databases_per_second 50 Maximum databases to process
per second. Should be tuned
according to individual
system specs. 0 is unlimited.
node_timeout 10 Request timeout to external
services
conn_timeout 0.5 Connection timeout to external
services
reclaim_age 604800 Time elapsed in seconds before
a container can be reclaimed
rsync_module {replication_ip}::container Format of the rsync module
where the replicator will send
data. The configuration value
can include some variables
that will be extracted from
the ring. Variables must
follow the format {NAME} where
NAME is one of: ip, port,
replication_ip,
replication_port, region,
zone, device, meta. See
etc/rsyncd.conf-sample for
some examples.
rsync_compress no Allow rsync to compress data
which is transmitted to
destination node during sync.
However, this is applicable
only when destination node is
in a different region than the
local one. NOTE: Objects that
are already compressed (for
example: .tar.gz, mp3) might
slow down the syncing process.
recon_cache_path /var/cache/swift Path to recon cache
nice_priority None Scheduling priority of server
processes. Niceness values
range from -20 (most favorable
to the process) to 19 (least
favorable to the process).
The default does not modify
priority.
ionice_class None I/O scheduling class of server
processes. I/O niceness class
values are
IOPRIO_CLASS_RT (realtime),
IOPRIO_CLASS_BE (best-effort),
and IOPRIO_CLASS_IDLE (idle).
The default does not modify
class and priority. Linux
supports io scheduling
priorities and classes since
2.6.13 with the CFQ io
scheduler.
Work only with ionice_priority.
ionice_priority None I/O scheduling priority of
server processes. I/O niceness
priority is a number which goes
from 0 to 7.
The higher the value, the lower
the I/O priority of the process.
Work only with ionice_class.
Ignored if IOPRIO_CLASS_IDLE
is set.
==================== =========================== =============================
*******************
[container-updater]
*******************
======================== ================= ==================================
Option Default Description
------------------------ ----------------- ----------------------------------
log_name container-updater Label used when logging
log_facility LOG_LOCAL0 Syslog log facility
log_level INFO Logging level
log_address /dev/log Logging directory
interval 300 Minimum time for a pass to take
concurrency 4 Number of updater workers to spawn
node_timeout 3 Request timeout to external
services
conn_timeout 0.5 Connection timeout to external
services
containers_per_second 50 Maximum containers updated per second.
Should be tuned according to individual
system specs. 0 is unlimited.
slowdown 0.01 Time in seconds to wait between
containers. Deprecated in favor of
containers_per_second.
account_suppression_time 60 Seconds to suppress updating an
account that has generated an
error (timeout, not yet found,
etc.)
recon_cache_path /var/cache/swift Path to recon cache
nice_priority None Scheduling priority of server
processes. Niceness values range
from -20 (most favorable to the
process) to 19 (least favorable
to the process). The default does
not modify priority.
ionice_class None I/O scheduling class of server
processes. I/O niceness class
values are IOPRIO_CLASS_RT (realtime),
IOPRIO_CLASS_BE (best-effort),
and IOPRIO_CLASS_IDLE (idle).
The default does not modify class and
priority. Linux supports io scheduling
priorities and classes since 2.6.13 with
the CFQ io scheduler.
Work only with ionice_priority.
ionice_priority None I/O scheduling priority of server
processes. I/O niceness priority is
a number which goes from 0 to 7.
The higher the value, the lower
the I/O priority of the process.
Work only with ionice_class.
Ignored if IOPRIO_CLASS_IDLE is set.
======================== ================= ==================================
*******************
[container-auditor]
*******************
===================== ================= =======================================
Option Default Description
--------------------- ----------------- ---------------------------------------
log_name container-auditor Label used when logging
log_facility LOG_LOCAL0 Syslog log facility
log_level INFO Logging level
log_address /dev/log Logging directory
interval 1800 Minimum time for a pass to take
containers_per_second 200 Maximum containers audited per second.
Should be tuned according to individual
system specs. 0 is unlimited.
recon_cache_path /var/cache/swift Path to recon cache
nice_priority None Scheduling priority of server processes.
Niceness values range from -20 (most
favorable to the process) to 19 (least
favorable to the process). The default
does not modify priority.
ionice_class None I/O scheduling class of server processes.
I/O niceness class values are
IOPRIO_CLASS_RT (realtime),
IOPRIO_CLASS_BE (best-effort),
and IOPRIO_CLASS_IDLE (idle).
The default does not modify class and
priority. Linux supports io scheduling
priorities and classes since 2.6.13 with
the CFQ io scheduler.
Work only with ionice_priority.
ionice_priority None I/O scheduling priority of server
processes. I/O niceness priority is
a number which goes from 0 to 7.
The higher the value, the lower the I/O
priority of the process. Work only with
ionice_class.
Ignored if IOPRIO_CLASS_IDLE is set.
===================== ================= =======================================
----------------------------
Account Server Configuration
----------------------------
An example Account Server configuration can be found at
etc/account-server.conf-sample in the source code repository.
The following configuration sections are available:
* :ref:`[DEFAULT] <account_server_default_options>`
* `[account-server]`_
* `[account-replicator]`_
* `[account-auditor]`_
* `[account-reaper]`_
.. _account_server_default_options:
*********
[DEFAULT]
*********
=============================== ========== =============================================
Option Default Description
------------------------------- ---------- ---------------------------------------------
swift_dir /etc/swift Swift configuration directory
devices /srv/node Parent directory or where devices are mounted
mount_check true Whether or not check if the devices are
mounted to prevent accidentally writing
to the root device
bind_ip 0.0.0.0 IP Address for server to bind to
bind_port 6202 Port for server to bind to
keep_idle 600 Value to set for socket TCP_KEEPIDLE
bind_timeout 30 Seconds to attempt bind before giving up
backlog 4096 Maximum number of allowed pending
connections
workers auto Override the number of pre-forked workers
that will accept connections. If set it
should be an integer, zero means no fork. If
unset, it will try to default to the number
of effective cpu cores and fallback to one.
Increasing the number of workers may reduce
the possibility of slow file system
operations in one request from negatively
impacting other requests. See
:ref:`general-service-tuning`.
max_clients 1024 Maximum number of clients one worker can
process simultaneously (it will actually
accept(2) N + 1). Setting this to one (1)
will only handle one request at a time,
without accepting another request
concurrently.
user swift User to run as
db_preallocation off If you don't mind the extra disk space usage in
overhead, you can turn this on to preallocate
disk space with SQLite databases to decrease
fragmentation.
disable_fallocate false Disable "fast fail" fallocate checks if the
underlying filesystem does not support it.
log_name swift Label used when logging
log_facility LOG_LOCAL0 Syslog log facility
log_level INFO Logging level
log_address /dev/log Logging directory
log_max_line_length 0 Caps the length of log lines to the
value given; no limit if set to 0, the
default.
log_custom_handlers None Comma-separated list of functions to call
to setup custom log handlers.
log_udp_host Override log_address
log_udp_port 514 UDP log port
log_statsd_host None Enables StatsD logging; IPv4/IPv6
address or a hostname. If a
hostname resolves to an IPv4 and IPv6
address, the IPv4 address will be
used.
log_statsd_port 8125
log_statsd_default_sample_rate 1.0
log_statsd_sample_rate_factor 1.0
log_statsd_metric_prefix
eventlet_debug false If true, turn on debug logging for eventlet
fallocate_reserve 1% You can set fallocate_reserve to the
number of bytes or percentage of disk
space you'd like fallocate to reserve,
whether there is space for the given
file size or not. Percentage will be used
if the value ends with a '%'. This is
useful for systems that behave badly when
they completely run out of space; you can
make the services pretend they're out of
space early.
nice_priority None Scheduling priority of server processes.
Niceness values range from -20 (most
favorable to the process) to 19 (least
favorable to the process). The default
does not modify priority.
ionice_class None I/O scheduling class of server processes.
I/O niceness class values are IOPRIO_CLASS_RT
(realtime), IOPRIO_CLASS_BE (best-effort),
and IOPRIO_CLASS_IDLE (idle).
The default does not modify class and
priority. Linux supports io scheduling
priorities and classes since 2.6.13 with
the CFQ io scheduler.
Work only with ionice_priority.
ionice_priority None I/O scheduling priority of server processes.
I/O niceness priority is a number which
goes from 0 to 7. The higher the value,
the lower the I/O priority of the process.
Work only with ionice_class.
Ignored if IOPRIO_CLASS_IDLE is set.
=============================== ========== =============================================
****************
[account-server]
****************
============================= ============== ==========================================
Option Default Description
----------------------------- -------------- ------------------------------------------
use Entry point for paste.deploy for the account
server. For most cases, this should be
`egg:swift#account`.
set log_name account-server Label used when logging
set log_facility LOG_LOCAL0 Syslog log facility
set log_level INFO Logging level
set log_requests True Whether or not to log each
request
set log_address /dev/log Logging directory
replication_server Configure parameter for creating
specific server. To handle all verbs,
including replication verbs, do not
specify "replication_server"
(this is the default). To only
handle replication, set to a True
value (e.g. "True" or "1").
To handle only non-replication
verbs, set to "False". Unless you
have a separate replication network, you
should not specify any value for
"replication_server".
nice_priority None Scheduling priority of server processes.
Niceness values range from -20 (most
favorable to the process) to 19 (least
favorable to the process). The default
does not modify priority.
ionice_class None I/O scheduling class of server processes.
I/O niceness class values are IOPRIO_CLASS_RT
(realtime), IOPRIO_CLASS_BE (best-effort),
and IOPRIO_CLASS_IDLE (idle).
The default does not modify class and
priority. Linux supports io scheduling
priorities and classes since 2.6.13 with
the CFQ io scheduler.
Work only with ionice_priority.
ionice_priority None I/O scheduling priority of server
processes. I/O niceness priority is
a number which goes from 0 to 7.
The higher the value, the lower the I/O
priority of the process. Work only with
ionice_class.
Ignored if IOPRIO_CLASS_IDLE is set.
============================= ============== ==========================================
********************
[account-replicator]
********************
==================== ========================= ===============================
Option Default Description
-------------------- ------------------------- -------------------------------
log_name account-replicator Label used when logging
log_facility LOG_LOCAL0 Syslog log facility
log_level INFO Logging level
log_address /dev/log Logging directory
per_diff 1000 Maximum number of database rows
that will be sync'd in a single
HTTP replication request.
Databases with less than or
equal to this number of
differing rows will always be
sync'd using an HTTP replication
request rather than using rsync.
max_diffs 100 Maximum number of HTTP
replication requests attempted
on each replication pass for any
one container. This caps how
long the replicator will spend
trying to sync a given database
per pass so the other databases
don't get starved.
concurrency 8 Number of replication workers
to spawn
interval 30 Time in seconds to wait between
replication passes
databases_per_second 50 Maximum databases to process
per second. Should be tuned
according to individual
system specs. 0 is unlimited.
node_timeout 10 Request timeout to external
services
conn_timeout 0.5 Connection timeout to external
services
reclaim_age 604800 Time elapsed in seconds before
an account can be reclaimed
rsync_module {replication_ip}::account Format of the rsync module where
the replicator will send data.
The configuration value can
include some variables that will
be extracted from the ring.
Variables must follow the format
{NAME} where NAME is one of: ip,
port, replication_ip,
replication_port, region, zone,
device, meta. See
etc/rsyncd.conf-sample for some
examples.
rsync_compress no Allow rsync to compress data
which is transmitted to
destination node during sync.
However, this is applicable only
when destination node is in a
different region than the local
one. NOTE: Objects that are
already compressed (for example:
.tar.gz, mp3) might slow down
the syncing process.
recon_cache_path /var/cache/swift Path to recon cache
nice_priority None Scheduling priority of server
processes. Niceness values
range from -20 (most favorable
to the process) to 19 (least
favorable to the process).
The default does not modify
priority.
ionice_class None I/O scheduling class of server
processes. I/O niceness class
values are IOPRIO_CLASS_RT
(realtime), IOPRIO_CLASS_BE
(best-effort), and IOPRIO_CLASS_IDLE
(idle).
The default does not modify
class and priority. Linux supports
io scheduling priorities and classes
since 2.6.13 with the CFQ io scheduler.
Work only with ionice_priority.
ionice_priority None I/O scheduling priority of server
processes. I/O niceness priority
is a number which goes from 0 to 7.
The higher the value, the lower
the I/O priority of the process.
Work only with ionice_class.
Ignored if IOPRIO_CLASS_IDLE
is set.
==================== ========================= ===============================
*****************
[account-auditor]
*****************
==================== ================ =======================================
Option Default Description
-------------------- ---------------- ---------------------------------------
log_name account-auditor Label used when logging
log_facility LOG_LOCAL0 Syslog log facility
log_level INFO Logging level
log_address /dev/log Logging directory
interval 1800 Minimum time for a pass to take
accounts_per_second 200 Maximum accounts audited per second.
Should be tuned according to individual
system specs. 0 is unlimited.
recon_cache_path /var/cache/swift Path to recon cache
nice_priority None Scheduling priority of server processes.
Niceness values range from -20 (most
favorable to the process) to 19 (least
favorable to the process). The default
does not modify priority.
ionice_class None I/O scheduling class of server processes.
I/O niceness class values are
IOPRIO_CLASS_RT (realtime),
IOPRIO_CLASS_BE (best-effort),
and IOPRIO_CLASS_IDLE (idle).
The default does not modify class and
priority. Linux supports io scheduling
priorities and classes since 2.6.13 with
the CFQ io scheduler.
Work only with ionice_priority.
ionice_priority None I/O scheduling priority of server
processes. I/O niceness priority is
a number which goes from 0 to 7.
The higher the value, the lower the I/O
priority of the process. Work only with
ionice_class.
Ignored if IOPRIO_CLASS_IDLE is set.
==================== ================ =======================================
****************
[account-reaper]
****************
================== =============== =========================================
Option Default Description
------------------ --------------- -----------------------------------------
log_name account-reaper Label used when logging
log_facility LOG_LOCAL0 Syslog log facility
log_level INFO Logging level
log_address /dev/log Logging directory
concurrency 25 Number of replication workers to spawn
interval 3600 Minimum time for a pass to take
node_timeout 10 Request timeout to external services
conn_timeout 0.5 Connection timeout to external services
delay_reaping 0 Normally, the reaper begins deleting
account information for deleted accounts
immediately; you can set this to delay
its work however. The value is in seconds,
2592000 = 30 days, for example. The sum of
this value and the container-updater
``interval`` should be less than the
account-replicator ``reclaim_age``. This
ensures that once the account-reaper has
deleted a container there is sufficient
time for the container-updater to report
to the account before the account DB is
removed.
reap_warn_after 2892000 If the account fails to be reaped due
to a persistent error, the account reaper
will log a message such as:
Account <name> has not been reaped since <date>
You can search logs for this message if
space is not being reclaimed after you
delete account(s). This is in addition to
any time requested by delay_reaping.
nice_priority None Scheduling priority of server processes.
Niceness values range from -20 (most
favorable to the process) to 19 (least
favorable to the process). The default
does not modify priority.
ionice_class None I/O scheduling class of server processes.
I/O niceness class values are IOPRIO_CLASS_RT
(realtime), IOPRIO_CLASS_BE (best-effort),
and IOPRIO_CLASS_IDLE (idle).
The default does not modify class and
priority. Linux supports io scheduling
priorities and classes since 2.6.13 with
the CFQ io scheduler.
Work only with ionice_priority.
ionice_priority None I/O scheduling priority of server
processes. I/O niceness priority is
a number which goes from 0 to 7.
The higher the value, the lower the I/O
priority of the process. Work only with
ionice_class.
Ignored if IOPRIO_CLASS_IDLE is set.
================== =============== =========================================
.. _proxy-server-config:
--------------------------
Proxy Server Configuration
--------------------------
An example Proxy Server configuration can be found at
etc/proxy-server.conf-sample in the source code repository.
The following configuration sections are available:
* :ref:`[DEFAULT] <proxy_server_default_options>`
* `[proxy-server]`_
* Individual sections for `Proxy middlewares`_
.. _proxy_server_default_options:
*********
[DEFAULT]
*********
==================================== ======================== ========================================
Option Default Description
------------------------------------ ------------------------ ----------------------------------------
bind_ip 0.0.0.0 IP Address for server to
bind to
bind_port 80 Port for server to bind to
keep_idle 600 Value to set for socket TCP_KEEPIDLE
bind_timeout 30 Seconds to attempt bind before
giving up
backlog 4096 Maximum number of allowed pending
connections
swift_dir /etc/swift Swift configuration directory
workers auto Override the number of
pre-forked workers that will
accept connections. If set it
should be an integer, zero
means no fork. If unset, it
will try to default to the
number of effective cpu cores
and fallback to one. See
:ref:`general-service-tuning`.
max_clients 1024 Maximum number of clients one
worker can process
simultaneously (it will
actually accept(2) N +
1). Setting this to one (1)
will only handle one request at
a time, without accepting
another request
concurrently.
user swift User to run as
cert_file Path to the ssl .crt. This
should be enabled for testing
purposes only.
key_file Path to the ssl .key. This
should be enabled for testing
purposes only.
cors_allow_origin List of origin hosts that are allowed
for CORS requests in addition to what
the container has set.
strict_cors_mode True If True (default) then CORS
requests are only allowed if their
Origin header matches an allowed
origin. Otherwise, any Origin is
allowed.
cors_expose_headers This is a list of headers that
are included in the header
Access-Control-Expose-Headers
in addition to what the container
has set.
client_timeout 60
trans_id_suffix This optional suffix (default is empty)
that would be appended to the swift
transaction id allows one to easily
figure out from which cluster that
X-Trans-Id belongs to. This is very
useful when one is managing more than
one swift cluster.
log_name swift Label used when logging
log_facility LOG_LOCAL0 Syslog log facility
log_level INFO Logging level
log_headers False
log_address /dev/log Logging directory
log_max_line_length 0 Caps the length of log
lines to the value given;
no limit if set to 0, the
default.
log_custom_handlers None Comma separated list of functions
to call to setup custom log
handlers.
log_udp_host Override log_address
log_udp_port 514 UDP log port
log_statsd_host None Enables StatsD logging; IPv4/IPv6
address or a hostname. If a
hostname resolves to an IPv4 and IPv6
address, the IPv4 address will be
used.
log_statsd_port 8125
log_statsd_default_sample_rate 1.0
log_statsd_sample_rate_factor 1.0
log_statsd_metric_prefix
eventlet_debug false If true, turn on debug logging
for eventlet
expose_info true Enables exposing configuration
settings via HTTP GET /info.
admin_key Key to use for admin calls that
are HMAC signed. Default
is empty, which will
disable admin calls to
/info.
disallowed_sections swift.valid_api_versions Allows the ability to withhold
sections from showing up in the
public calls to /info. You can
withhold subsections by separating
the dict level with a ".".
expiring_objects_container_divisor 86400
expiring_objects_account_name expiring_objects
nice_priority None Scheduling priority of server
processes.
Niceness values range from -20 (most
favorable to the process) to 19 (least
favorable to the process). The default
does not modify priority.
ionice_class None I/O scheduling class of server
processes. I/O niceness class values
are IOPRIO_CLASS_RT (realtime),
IOPRIO_CLASS_BE (best-effort) and
IOPRIO_CLASS_IDLE (idle).
The default does not
modify class and priority. Linux
supports io scheduling priorities
and classes since 2.6.13 with
the CFQ io scheduler.
Work only with ionice_priority.
ionice_priority None I/O scheduling priority of server
processes. I/O niceness priority is
a number which goes from 0 to 7.
The higher the value, the lower
the I/O priority of the process.
Work only with ionice_class.
Ignored if IOPRIO_CLASS_IDLE is set.
==================================== ======================== ========================================
**************
[proxy-server]
**************
====================================== =============== =====================================
Option Default Description
-------------------------------------- --------------- -------------------------------------
use Entry point for paste.deploy for
the proxy server. For most
cases, this should be
`egg:swift#proxy`.
set log_name proxy-server Label used when logging
set log_facility LOG_LOCAL0 Syslog log facility
set log_level INFO Log level
set log_headers True If True, log headers in each
request
set log_handoffs True If True, the proxy will log
whenever it has to failover to a
handoff node
recheck_account_existence 60 Cache timeout in seconds to
send memcached for account
existence
recheck_container_existence 60 Cache timeout in seconds to
send memcached for container
existence
object_chunk_size 65536 Chunk size to read from
object servers
client_chunk_size 65536 Chunk size to read from
clients
memcache_servers 127.0.0.1:11211 Comma separated list of
memcached servers
ip:port or [ipv6addr]:port
memcache_max_connections 2 Max number of connections to
each memcached server per
worker
node_timeout 10 Request timeout to external
services
recoverable_node_timeout node_timeout Request timeout to external
services for requests that, on
failure, can be recovered
from. For example, object GET.
client_timeout 60 Timeout to read one chunk
from a client
conn_timeout 0.5 Connection timeout to
external services
error_suppression_interval 60 Time in seconds that must
elapse since the last error
for a node to be considered
no longer error limited
error_suppression_limit 10 Error count to consider a
node error limited
allow_account_management false Whether account PUTs and DELETEs
are even callable
account_autocreate false If set to 'true' authorized
accounts that do not yet exist
within the Swift cluster will
be automatically created.
max_containers_per_account 0 If set to a positive value,
trying to create a container
when the account already has at
least this maximum containers
will result in a 403 Forbidden.
Note: This is a soft limit,
meaning a user might exceed the
cap for
recheck_account_existence before
the 403s kick in.
max_containers_whitelist This is a comma separated list
of account names that ignore
the max_containers_per_account
cap.
rate_limit_after_segment 10 Rate limit the download of
large object segments after
this segment is downloaded.
rate_limit_segments_per_sec 1 Rate limit large object
downloads at this rate.
request_node_count 2 * replicas Set to the number of nodes to
contact for a normal request.
You can use '* replicas' at the
end to have it use the number
given times the number of
replicas for the ring being used
for the request.
swift_owner_headers <see the sample These are the headers whose
conf file for values will only be shown to
the list of swift_owners. The exact
default definition of a swift_owner is
headers> up to the auth system in use,
but usually indicates
administrative responsibilities.
sorting_method shuffle Storage nodes can be chosen at
random (shuffle), by using timing
measurements (timing), or by using
an explicit match (affinity).
Using timing measurements may allow
for lower overall latency, while
using affinity allows for finer
control. In both the timing and
affinity cases, equally-sorting nodes
are still randomly chosen to spread
load. This option may be overridden
in a per-policy configuration
section.
timing_expiry 300 If the "timing" sorting_method is
used, the timings will only be valid
for the number of seconds configured
by timing_expiry.
concurrent_gets off Use replica count number of
threads concurrently during a
GET/HEAD and return with the
first successful response. In
the EC case, this parameter only
affects an EC HEAD as an EC GET
behaves differently.
concurrency_timeout conn_timeout This parameter controls how long
to wait before firing off the
next concurrent_get thread. A
value of 0 would we fully concurrent,
any other number will stagger the
firing of the threads. This number
should be between 0 and node_timeout.
The default is conn_timeout (0.5).
nice_priority None Scheduling priority of server
processes.
Niceness values range from -20 (most
favorable to the process) to 19 (least
favorable to the process). The default
does not modify priority.
ionice_class None I/O scheduling class of server
processes. I/O niceness class values
are IOPRIO_CLASS_RT (realtime),
IOPRIO_CLASS_BE (best-effort),
and IOPRIO_CLASS_IDLE (idle).
The default does not modify class and
priority. Linux supports io scheduling
priorities and classes since 2.6.13
with the CFQ io scheduler.
Work only with ionice_priority.
ionice_priority None I/O scheduling priority of server
processes. I/O niceness priority is
a number which goes from 0 to 7.
The higher the value, the lower the
I/O priority of the process. Work
only with ionice_class.
Ignored if IOPRIO_CLASS_IDLE is set.
read_affinity None Specifies which backend servers to
prefer on reads; used in conjunction
with the sorting_method option being
set to 'affinity'. Format is a comma
separated list of affinity descriptors
of the form <selection>=<priority>.
The <selection> may be r<N> for
selecting nodes in region N or
r<N>z<M> for selecting nodes in
region N, zone M. The <priority>
value should be a whole number
that represents the priority to
be given to the selection; lower
numbers are higher priority.
Default is empty, meaning no
preference. This option may be
overridden in a per-policy
configuration section.
write_affinity None Specifies which backend servers to
prefer on writes. Format is a comma
separated list of affinity
descriptors of the form r<N> for
region N or r<N>z<M> for region N,
zone M. Default is empty, meaning no
preference. This option may be
overridden in a per-policy
configuration section.
write_affinity_node_count 2 * replicas The number of local (as governed by
the write_affinity setting) nodes to
attempt to contact first on writes,
before any non-local ones. The value
should be an integer number, or use
'* replicas' at the end to have it
use the number given times the number
of replicas for the ring being used
for the request. This option may be
overridden in a per-policy
configuration section.
write_affinity_handoff_delete_count auto The number of local (as governed by
the write_affinity setting) handoff
nodes to attempt to contact on
deletion, in addition to primary
nodes. Example: in geographically
distributed deployment, If replicas=3,
sometimes there may be 1 primary node
and 2 local handoff nodes in one region
holding the object after uploading but
before object replicated to the
appropriate locations in other regions.
In this case, include these handoff
nodes to send request when deleting
object could help make correct decision
for the response. The default value 'auto'
means Swift will calculate the number
automatically, the default value is
(replicas - len(local_primary_nodes)).
This option may be overridden in a
per-policy configuration section.
====================================== =============== =====================================
.. _proxy_server_per_policy_config:
************************
Per policy configuration
************************
Some proxy-server configuration options may be overridden for individual
:doc:`overview_policies` by including per-policy config section(s). These
options are:
- ``sorting_method``
- ``read_affinity``
- ``write_affinity``
- ``write_affinity_node_count``
- ``write_affinity_handoff_delete_count``
The per-policy config section name must be of the form::
[proxy-server:policy:<policy index>]
.. note::
The per-policy config section name should refer to the policy index, not
the policy name.
.. note::
The first part of proxy-server config section name must match the name of
the proxy-server config section. This is typically ``proxy-server`` as
shown above, but if different then the names of any per-policy config
sections must be changed accordingly.
The value of an option specified in a per-policy section will override any
value given in the proxy-server section for that policy only. Otherwise the
value of these options will be that specified in the proxy-server section.
For example, the following section provides policy-specific options for a
policy with index ``3``::
[proxy-server:policy:3]
sorting_method = affinity
read_affinity = r2=1
write_affinity = r2
write_affinity_node_count = 1 * replicas
write_affinity_handoff_delete_count = 2
.. note::
It is recommended that per-policy config options are *not* included in the
``[DEFAULT]`` section. If they are then the following behavior applies.
Per-policy config sections will inherit options in the ``[DEFAULT]``
section of the config file, and any such inheritance will take precedence
over inheriting options from the proxy-server config section.
Per-policy config section options will override options in the
``[DEFAULT]`` section. Unlike the behavior described under `General Server
Configuration`_ for paste-deploy ``filter`` and ``app`` sections, the
``set`` keyword is not required for options to override in per-policy
config sections.
For example, given the following settings in a config file::
[DEFAULT]
sorting_method = affinity
read_affinity = r0=100
write_affinity = r0
[app:proxy-server]
use = egg:swift#proxy
# use of set keyword here overrides [DEFAULT] option
set read_affinity = r1=100
# without set keyword, [DEFAULT] option overrides in a paste-deploy section
write_affinity = r1
[proxy-server:policy:0]
sorting_method = affinity
# set keyword not required here to override [DEFAULT] option
write_affinity = r1
would result in policy with index ``0`` having settings:
* ``read_affinity = r0=100`` (inherited from the ``[DEFAULT]`` section)
* ``write_affinity = r1`` (specified in the policy 0 section)
and any other policy would have the default settings of:
* ``read_affinity = r1=100`` (set in the proxy-server section)
* ``write_affinity = r0`` (inherited from the ``[DEFAULT]`` section)
*****************
Proxy Middlewares
*****************
Many features in Swift are implemented as middleware in the proxy-server
pipeline. See :doc:`middleware` and the ``proxy-server.conf-sample`` file for
more information. In particular, the use of some type of :doc:`authentication
and authorization middleware <overview_auth>` is highly recommended.
------------------------
Memcached Considerations
------------------------
Several of the Services rely on Memcached for caching certain types of
lookups, such as auth tokens, and container/account existence. Swift does
not do any caching of actual object data. Memcached should be able to run
on any servers that have available RAM and CPU. At Rackspace, we run
Memcached on the proxy servers. The `memcache_servers` config option
in the `proxy-server.conf` should contain all memcached servers.
-----------
System Time
-----------
Time may be relative but it is relatively important for Swift! Swift uses
timestamps to determine which is the most recent version of an object.
It is very important for the system time on each server in the cluster to
by synced as closely as possible (more so for the proxy server, but in general
it is a good idea for all the servers). At Rackspace, we use NTP with a local
NTP server to ensure that the system times are as close as possible. This
should also be monitored to ensure that the times do not vary too much.
.. _general-service-tuning:
----------------------
General Service Tuning
----------------------
Most services support either a `worker` or `concurrency` value in the
settings. This allows the services to make effective use of the cores
available. A good starting point to set the concurrency level for the proxy
and storage services to 2 times the number of cores available. If more than
one service is sharing a server, then some experimentation may be needed to
find the best balance.
At Rackspace, our Proxy servers have dual quad core processors, giving us 8
cores. Our testing has shown 16 workers to be a pretty good balance when
saturating a 10g network and gives good CPU utilization.
Our Storage server processes all run together on the same servers. These servers have
dual quad core processors, for 8 cores total. We run the Account, Container,
and Object servers with 8 workers each. Most of the background jobs are run at
a concurrency of 1, with the exception of the replicators which are run at a
concurrency of 2.
The `max_clients` parameter can be used to adjust the number of client
requests an individual worker accepts for processing. The fewer requests being
processed at one time, the less likely a request that consumes the worker's
CPU time, or blocks in the OS, will negatively impact other requests. The more
requests being processed at one time, the more likely one worker can utilize
network and disk capacity.
On systems that have more cores, and more memory, where one can afford to run
more workers, raising the number of workers and lowering the maximum number of
clients serviced per worker can lessen the impact of CPU intensive or stalled
requests.
The `nice_priority` parameter can be used to set program scheduling priority.
The `ionice_class` and `ionice_priority` parameters can be used to set I/O scheduling
class and priority on the systems that use an I/O scheduler that supports
I/O priorities. As at kernel 2.6.17 the only such scheduler is the Completely
Fair Queuing (CFQ) I/O scheduler. If you run your Storage servers all together
on the same servers, you can slow down the auditors or prioritize
object-server I/O via these parameters (but probably do not need to change
it on the proxy). It is a new feature and the best practices are still
being developed. On some systems it may be required to run the daemons as root.
For more info also see setpriority(2) and ioprio_set(2).
The above configuration setting should be taken as suggestions and testing
of configuration settings should be done to ensure best utilization of CPU,
network connectivity, and disk I/O.
-------------------------
Filesystem Considerations
-------------------------
Swift is designed to be mostly filesystem agnostic--the only requirement
being that the filesystem supports extended attributes (xattrs). After
thorough testing with our use cases and hardware configurations, XFS was
the best all-around choice. If you decide to use a filesystem other than
XFS, we highly recommend thorough testing.
For distros with more recent kernels (for example Ubuntu 12.04 Precise),
we recommend using the default settings (including the default inode size
of 256 bytes) when creating the file system::
mkfs.xfs -L D1 /dev/sda1
In the last couple of years, XFS has made great improvements in how inodes
are allocated and used. Using the default inode size no longer has an
impact on performance.
For distros with older kernels (for example Ubuntu 10.04 Lucid),
some settings can dramatically impact performance. We recommend the
following when creating the file system::
mkfs.xfs -i size=1024 -L D1 /dev/sda1
Setting the inode size is important, as XFS stores xattr data in the inode.
If the metadata is too large to fit in the inode, a new extent is created,
which can cause quite a performance problem. Upping the inode size to 1024
bytes provides enough room to write the default metadata, plus a little
headroom.
The following example mount options are recommended when using XFS::
mount -t xfs -o noatime,nodiratime,logbufs=8 -L D1 /srv/node/d1
We do not recommend running Swift on RAID, but if you are using
RAID it is also important to make sure that the proper sunit and swidth
settings get set so that XFS can make most efficient use of the RAID array.
For a standard Swift install, all data drives are mounted directly under
``/srv/node`` (as can be seen in the above example of mounting label ``D1``
as ``/srv/node/d1``). If you choose to mount the drives in another directory,
be sure to set the `devices` config option in all of the server configs to
point to the correct directory.
The mount points for each drive in ``/srv/node/`` should be owned by the root user
almost exclusively (``root:root 755``). This is required to prevent rsync from
syncing files into the root drive in the event a drive is unmounted.
Swift uses system calls to reserve space for new objects being written into
the system. If your filesystem does not support `fallocate()` or
`posix_fallocate()`, be sure to set the `disable_fallocate = true` config
parameter in account, container, and object server configs.
Most current Linux distributions ship with a default installation of updatedb.
This tool runs periodically and updates the file name database that is used by
the GNU locate tool. However, including Swift object and container database
files is most likely not required and the periodic update affects the
performance quite a bit. To disable the inclusion of these files add the path
where Swift stores its data to the setting PRUNEPATHS in `/etc/updatedb.conf`::
PRUNEPATHS="... /tmp ... /var/spool ... /srv/node"
---------------------
General System Tuning
---------------------
Rackspace currently runs Swift on Ubuntu Server 10.04, and the following
changes have been found to be useful for our use cases.
The following settings should be in `/etc/sysctl.conf`::
# disable TIME_WAIT.. wait..
net.ipv4.tcp_tw_recycle=1
net.ipv4.tcp_tw_reuse=1
# disable syn cookies
net.ipv4.tcp_syncookies = 0
# double amount of allowed conntrack
net.ipv4.netfilter.ip_conntrack_max = 262144
To load the updated sysctl settings, run ``sudo sysctl -p``.
A note about changing the TIME_WAIT values. By default the OS will hold
a port open for 60 seconds to ensure that any remaining packets can be
received. During high usage, and with the number of connections that are
created, it is easy to run out of ports. We can change this since we are
in control of the network. If you are not in control of the network, or
do not expect high loads, then you may not want to adjust those values.
----------------------
Logging Considerations
----------------------
Swift is set up to log directly to syslog. Every service can be configured
with the `log_facility` option to set the syslog log facility destination.
We recommended using syslog-ng to route the logs to specific log
files locally on the server and also to remote log collecting servers.
Additionally, custom log handlers can be used via the custom_log_handlers
setting.