![Tom Fifield](/assets/img/avatar_default.png)
The documentation includes workarounds due to bugs, which can be solved after some time. This patch removes references to bugs which have been solved. Change-Id: I4e4cb3bb70b3b9f68e995d00cc83cb8db1d19499
717 lines
38 KiB
XML
717 lines
38 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
|
|
<!DOCTYPE section [
|
|
<!-- Some useful entities borrowed from HTML -->
|
|
<!ENTITY nbsp " ">
|
|
<!ENTITY mdash "—">
|
|
]>
|
|
<section xml:id="section_compute-scheduler"
|
|
xmlns="http://docbook.org/ns/docbook"
|
|
xmlns:xlink="http://www.w3.org/1999/xlink"
|
|
xmlns:xi="http://www.w3.org/2001/XInclude"
|
|
xmlns:ns5="http://www.w3.org/1999/xhtml"
|
|
xmlns:ns4="http://www.w3.org/2000/svg"
|
|
xmlns:ns3="http://www.w3.org/1998/Math/MathML"
|
|
xmlns:ns="http://docbook.org/ns/docbook" version="5.0">
|
|
<?dbhtml stop-chunking?>
|
|
<title>Scheduling</title>
|
|
<para>Compute uses the <systemitem class="service"
|
|
>nova-scheduler</systemitem> service to determine how to
|
|
dispatch compute and volume requests. For example, the
|
|
<systemitem class="service">nova-scheduler</systemitem>
|
|
service determines which host a VM should launch on. The term
|
|
<firstterm>host</firstterm> in the context of filters
|
|
means a physical node that has a <systemitem class="service"
|
|
>nova-compute</systemitem> service running on it. You can
|
|
configure the scheduler through a variety of options.</para>
|
|
<para>Compute is configured with the following default scheduler options in the
|
|
<filename>/etc/nova/nova.conf</filename> file:</para>
|
|
<programlisting language="ini">scheduler_driver=nova.scheduler.multi.MultiScheduler
|
|
scheduler_driver_task_period=60
|
|
compute_scheduler_driver=nova.scheduler.filter_scheduler.FilterScheduler
|
|
scheduler_available_filters=nova.scheduler.filters.all_filters
|
|
scheduler_default_filters=RetryFilter,AvailabilityZoneFilter,RamFilter,ComputeFilter,ComputeCapabilitiesFilter,ImagePropertiesFilter,ServerGroupAntiAffinityFilter,ServerGroupAffinityFilter</programlisting>
|
|
<para>By default, the scheduler_driver is configured as a filter
|
|
scheduler, as described in the next section. In the default
|
|
configuration, this scheduler considers hosts that meet all
|
|
the following criteria:</para>
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para>Have not been attempted for scheduling purposes
|
|
(<literal>RetryFilter</literal>).</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>Are in the requested availability zone
|
|
(<literal>AvailabilityZoneFilter</literal>).</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>Have sufficient RAM available
|
|
(<literal>RamFilter</literal>).</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>Are capable of servicing the request
|
|
(<literal>ComputeFilter</literal>).</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>Satisfy the extra specs associated with the instance
|
|
type
|
|
(<literal>ComputeCapabilitiesFilter</literal>).</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>Satisfy any architecture, hypervisor type, or
|
|
virtual machine mode properties specified on the
|
|
instance's image properties.
|
|
(<literal>ImagePropertiesFilter</literal>).</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
<para>The scheduler caches its list of available hosts; you can
|
|
specify how often the list is updated by modifying the
|
|
<option>scheduler_driver_task_period</option> value.
|
|
</para>
|
|
|
|
<note>
|
|
<para>Do not configure <option>service_down_time</option> to be
|
|
much smaller than <option>scheduler_driver_task_period</option>;
|
|
otherwise, hosts will appear to be dead while the host list is
|
|
being cached.</para>
|
|
</note>
|
|
<para>For information on the volume scheduler, refer the Block
|
|
Storage section of <link
|
|
xlink:href="http://docs.openstack.org/admin-guide-cloud/content/managing-volumes.html">
|
|
<citetitle>OpenStack Cloud Administrator
|
|
Guide</citetitle></link> for information.</para>
|
|
<section xml:id="filter-scheduler">
|
|
<title>Filter scheduler</title>
|
|
<para>The Filter Scheduler
|
|
(<literal>nova.scheduler.filter_scheduler.FilterScheduler</literal>)
|
|
is the default scheduler for scheduling virtual machine
|
|
instances. It supports filtering and weighting to make
|
|
informed decisions on where a new instance should be
|
|
created.</para>
|
|
</section>
|
|
<section xml:id="scheduler-filters">
|
|
<?dbhtml stop-chunking?>
|
|
<title>Filters</title>
|
|
<para>When the Filter Scheduler receives a request for a
|
|
resource, it first applies filters to determine which
|
|
hosts are eligible for consideration when dispatching a
|
|
resource. Filters are binary: either a host is accepted by
|
|
the filter, or it is rejected. Hosts that are accepted by
|
|
the filter are then processed by a different algorithm to
|
|
decide which hosts to use for that request, described in
|
|
the <link linkend="weights">Weights</link> section.
|
|
<figure xml:id="filter-figure">
|
|
<title>Filtering</title>
|
|
<mediaobject>
|
|
<imageobject>
|
|
<imagedata
|
|
fileref="../../common/figures/filteringWorkflow1.png"
|
|
scale="80"/>
|
|
</imageobject>
|
|
</mediaobject>
|
|
</figure>
|
|
</para>
|
|
<para>The <literal>scheduler_available_filters</literal>
|
|
configuration option in <filename>nova.conf</filename>
|
|
provides the Compute service with the list of the filters
|
|
that are used by the scheduler. The default setting
|
|
specifies all of the filter that are included with the
|
|
Compute service:</para>
|
|
<programlisting language="ini">scheduler_available_filters=nova.scheduler.filters.all_filters</programlisting>
|
|
<para>This configuration option can be specified multiple
|
|
times. For example, if you implemented your own custom
|
|
filter in Python called
|
|
<literal>myfilter.MyFilter</literal> and you wanted to
|
|
use both the built-in filters and your custom filter, your
|
|
<filename>nova.conf</filename> file would
|
|
contain:</para>
|
|
<programlisting language="ini">scheduler_available_filters=nova.scheduler.filters.all_filters
|
|
scheduler_available_filters=myfilter.MyFilter</programlisting>
|
|
<para>The <literal>scheduler_default_filters</literal> configuration option in
|
|
<filename>nova.conf</filename> defines the list of filters that are applied by the
|
|
<systemitem class="service">nova-scheduler</systemitem> service. The default filters
|
|
are:</para>
|
|
<programlisting language="ini">scheduler_default_filters=RetryFilter,AvailabilityZoneFilter,RamFilter,ComputeFilter,ComputeCapabilitiesFilter,ImagePropertiesFilter,ServerGroupAntiAffinityFilter,ServerGroupAffinityFilter</programlisting>
|
|
<para>The following sections describe the available
|
|
filters.</para>
|
|
<section xml:id="aggregatecorefilter">
|
|
<title>AggregateCoreFilter</title>
|
|
<para>Implements blueprint per-aggregate-resource-ratio.
|
|
AggregateCoreFilter supports per-aggregate
|
|
<literal>cpu_allocation_ratio</literal>. If the
|
|
per-aggregate value is not found, the value falls back
|
|
to the global setting.</para>
|
|
</section>
|
|
<section xml:id="aggregateimagepropertiesisolationfilter">
|
|
<title>AggregateImagePropertiesIsolation</title>
|
|
<para>Matches properties defined in an image's metadata against those of aggregates to
|
|
determine host matches:</para>
|
|
<para>
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para>If a host belongs to an aggregate and the aggregate defines one or
|
|
more metadata that match an image's properties, that host is a candidate
|
|
to boot the image's instance.</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>If a host does not belong to any aggregate, it can boot instances from
|
|
all images.</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
</para>
|
|
<para>For example, the following aggregate <systemitem>myWinAgg</systemitem> has the
|
|
Windows operating system as metadata (named 'windows'):</para>
|
|
<screen><prompt>$</prompt> <userinput>nova aggregate-details MyWinAgg</userinput>
|
|
<computeroutput>+----+----------+-------------------+------------+---------------+
|
|
| Id | Name | Availability Zone | Hosts | Metadata |
|
|
+----+----------+-------------------+------------+---------------+
|
|
| 1 | MyWinAgg | None | 'sf-devel' | 'os=windows' |
|
|
+----+----------+-------------------+------------+---------------+</computeroutput></screen>
|
|
<para>In this example, because the following Win-2012 image has the <property>windows</property>
|
|
property, it would boot on the <systemitem>sf-devel</systemitem> host (all other
|
|
filters being equal):</para>
|
|
<screen><prompt>$</prompt> <userinput>glance image-show Win-2012</userinput>
|
|
<computeroutput>+------------------+--------------------------------------+
|
|
| Property | Value |
|
|
+------------------+--------------------------------------+
|
|
| Property 'os' | windows |
|
|
| checksum | f8a2eeee2dc65b3d9b6e63678955bd83 |
|
|
| container_format | ami |
|
|
| created_at | 2013-11-14T13:24:25 |
|
|
| ...</computeroutput></screen>
|
|
<para>You can configure the <systemitem>AggregateImagePropertiesIsolation</systemitem> filter using
|
|
the following options in the <filename>nova.conf</filename> file:
|
|
</para>
|
|
<programlisting language="ini"># Considers only keys matching the given namespace (string).
|
|
aggregate_image_properties_isolation_namespace=<None>
|
|
|
|
# Separator used between the namespace and keys (string).
|
|
aggregate_image_properties_isolation_separator=.</programlisting>
|
|
</section>
|
|
<section xml:id="aggregateinstanceextraspecsfilter">
|
|
<title>AggregateInstanceExtraSpecsFilter</title>
|
|
<para>Matches properties defined in an instance type's
|
|
extra specs against admin-defined properties on a host
|
|
aggregate. Works with specifications that are
|
|
unscoped, or are scoped with
|
|
<literal>aggregate_instance_extra_specs</literal>.
|
|
See the <link linkend="host-aggregates">host
|
|
aggregates</link> section for documentation on how
|
|
to use this filter.</para>
|
|
</section>
|
|
<section xml:id="aggregate-multi-tenancy-isolation">
|
|
<title>AggregateMultiTenancyIsolation</title>
|
|
<para>Isolates tenants to specific <link
|
|
linkend="host-aggregates">host aggregates</link>.
|
|
If a host is in an aggregate that has the metadata key
|
|
<literal>filter_tenant_id</literal> it only
|
|
creates instances from that tenant (or list of
|
|
tenants). A host can be in different aggregates. If a
|
|
host does not belong to an aggregate with the metadata
|
|
key, it can create instances from all tenants.</para>
|
|
</section>
|
|
<section xml:id="aggregate-ram-filter">
|
|
<title>AggregateRamFilter</title>
|
|
<para>Implements blueprint
|
|
<literal>per-aggregate-resource-ratio</literal>.
|
|
Supports per-aggregate
|
|
<literal>ram_allocation_ratio</literal>. If
|
|
per-aggregate value is not found, it falls back to the
|
|
default setting.</para>
|
|
</section>
|
|
<section xml:id="allhostsfilter">
|
|
<title>AllHostsFilter</title>
|
|
<para>This is a no-op filter, it does not eliminate any of
|
|
the available hosts.</para>
|
|
</section>
|
|
<section xml:id="availabilityzonefilter">
|
|
<title>AvailabilityZoneFilter</title>
|
|
<para>Filters hosts by availability zone. This filter must
|
|
be enabled for the scheduler to respect availability
|
|
zones in requests.</para>
|
|
</section>
|
|
<section xml:id="computecapabilitiesfilter">
|
|
<title>ComputeCapabilitiesFilter</title>
|
|
<para>Matches properties defined in an instance type's
|
|
extra specs against compute capabilities.</para>
|
|
<para>If an extra specs key contains a colon ":", anything
|
|
before the colon is treated as a namespace, and
|
|
anything after the colon is treated as the key to be
|
|
matched. If a namespace is present and is not
|
|
'capabilities', it is ignored by this filter.</para>
|
|
</section>
|
|
<section xml:id="computefilter">
|
|
<title>ComputeFilter</title>
|
|
<para>Passes all hosts that are operational and
|
|
enabled.</para>
|
|
<para>In general, this filter should always be enabled.
|
|
</para>
|
|
</section>
|
|
<section xml:id="corefilter">
|
|
<title>CoreFilter</title>
|
|
<para>Only schedule instances on hosts if there are
|
|
sufficient CPU cores available. If this filter is not
|
|
set, the scheduler may over provision a host based on
|
|
cores (for example, the virtual cores running on an
|
|
instance may exceed the physical cores).</para>
|
|
<para>This filter can be configured to allow a fixed
|
|
amount of vCPU overcommitment by using the
|
|
<option>cpu_allocation_ratio</option>
|
|
Configuration option in
|
|
<filename>nova.conf</filename>. The default setting
|
|
is:</para>
|
|
<programlisting language="ini">cpu_allocation_ratio=16.0</programlisting>
|
|
<para>With this setting, if 8 vCPUs are on a node, the
|
|
scheduler allows instances up to 128 vCPU to be run on
|
|
that node.</para>
|
|
<para>To disallow vCPU overcommitment set:</para>
|
|
<programlisting language="ini">cpu_allocation_ratio=1.0</programlisting>
|
|
<note>
|
|
<para>
|
|
The Compute API will always return the actual number of CPU
|
|
cores available on a compute node regardless of the value of
|
|
the <option>cpu_allocation_ratio</option> configuration key. As
|
|
a result changes to the <option>cpu_allocation_ratio</option>
|
|
are not reflected via the command line clients or the
|
|
dashboard. Changes to this configuration key are only taken
|
|
into account internally in the scheduler.
|
|
</para>
|
|
</note>
|
|
</section>
|
|
<section xml:id="differenthostfilter">
|
|
<title>DifferentHostFilter</title>
|
|
<para>Schedule the instance on a different host from a set
|
|
of instances. To take advantage of this filter, the
|
|
requester must pass a scheduler hint, using
|
|
<literal>different_host</literal> as the key and a
|
|
list of instance uuids as the value. This filter is
|
|
the opposite of the <literal>SameHostFilter</literal>.
|
|
Using the <command>nova</command> command-line tool,
|
|
use the <literal>--hint</literal> flag. For
|
|
example:</para>
|
|
<screen><prompt>$</prompt> <userinput>nova boot --image cedef40a-ed67-4d10-800e-17455edce175 --flavor 1 \
|
|
--hint different_host=a0cf03a5-d921-4877-bb5c-86d26cf818e1 \
|
|
--hint different_host=8c19174f-4220-44f0-824a-cd1eeef10287 server-1</userinput></screen>
|
|
<para>With the API, use the
|
|
<literal>os:scheduler_hints</literal> key. For
|
|
example:</para>
|
|
<programlisting language="json"><xi:include href="../../common/samples/server-scheduler-hints.json" parse="text"/></programlisting>
|
|
</section>
|
|
<section xml:id="diskfilter">
|
|
<title>DiskFilter</title>
|
|
<para>Only schedule instances on hosts if there is
|
|
sufficient disk space available for root and ephemeral
|
|
storage.</para>
|
|
<para>This filter can be configured to allow a fixed
|
|
amount of disk overcommitment by using the
|
|
<literal>disk_allocation_ratio</literal>
|
|
Configuration option in
|
|
<filename>nova.conf</filename>. The default setting
|
|
is:</para>
|
|
<programlisting language="ini">disk_allocation_ratio=1.0</programlisting>
|
|
<para>Adjusting this value to greater than 1.0 enables
|
|
scheduling instances while over committing disk
|
|
resources on the node. This might be desirable if you
|
|
use an image format that is sparse or copy on write
|
|
such that each virtual instance does not require a 1:1
|
|
allocation of virtual disk to physical storage.</para>
|
|
</section>
|
|
<section xml:id="groupaffinityfilter">
|
|
<title>GroupAffinityFilter</title>
|
|
<para>The GroupAffinityFilter ensures that an instance is
|
|
scheduled on to a host from a set of group hosts. To
|
|
take advantage of this filter, the requester must pass
|
|
a scheduler hint, using <literal>group</literal> as
|
|
the key and an arbitrary name as the value. Using the
|
|
<command>nova</command> command-line tool, use the
|
|
<literal>--hint</literal> flag. For
|
|
example:</para>
|
|
<screen><prompt>$</prompt> <userinput>nova boot --image cedef40a-ed67-4d10-800e-17455edce175 --flavor 1 \
|
|
--hint group=foo server-1</userinput></screen>
|
|
</section>
|
|
<section xml:id="groupantiaffinityfilter">
|
|
<title>GroupAntiAffinityFilter</title>
|
|
<para>The GroupAntiAffinityFilter ensures that each
|
|
instance in a group is on a different host. To take
|
|
advantage of this filter, the requester must pass a
|
|
scheduler hint, using <literal>group</literal> as the
|
|
key and an arbitrary name as the value. Using the
|
|
<command>nova</command> command-line tool, use the
|
|
<literal>--hint</literal> flag. For
|
|
example:</para>
|
|
<screen><prompt>$</prompt> <userinput>nova boot --image cedef40a-ed67-4d10-800e-17455edce175 --flavor 1 \
|
|
--hint group=foo server-1</userinput></screen>
|
|
</section>
|
|
<section xml:id="imagepropertiesfilter">
|
|
<title>ImagePropertiesFilter</title>
|
|
<para>Filters hosts based on properties defined on the
|
|
instance's image. It passes hosts that can support the
|
|
specified image properties contained in the instance.
|
|
Properties include the architecture, hypervisor type,
|
|
and virtual machine mode. for example, an instance
|
|
might require a host that runs an ARM-based processor
|
|
and QEMU as the hypervisor. An image can be decorated
|
|
with these properties by using:</para>
|
|
<screen><prompt>$</prompt> <userinput>glance image-update img-uuid --property architecture=arm --property hypervisor_type=qemu</userinput></screen>
|
|
<para>The image properties that the filter checks for
|
|
are:</para>
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para><literal>architecture</literal>:
|
|
Architecture describes the machine
|
|
architecture required by the image. Examples
|
|
are i686, x86_64, arm, and ppc64.</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para><literal>hypervisor_type</literal>:
|
|
Hypervisor type describes the hypervisor
|
|
required by the image. Examples are xen, kvm,
|
|
qemu, and xenapi.</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para><literal>vm_mode</literal>: Virtual machine
|
|
mode describes the hypervisor application
|
|
binary interface (ABI) required by the image.
|
|
Examples are 'xen' for Xen 3.0 paravirtual
|
|
ABI, 'hvm' for native ABI, 'uml' for User Mode
|
|
Linux paravirtual ABI, exe for container virt
|
|
executable ABI.</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
</section>
|
|
<section xml:id="isolatedhostsfilter">
|
|
<title>IsolatedHostsFilter</title>
|
|
<para>Allows the admin to define a special (isolated) set
|
|
of images and a special (isolated) set of hosts, such
|
|
that the isolated images can only run on the isolated
|
|
hosts, and the isolated hosts can only run isolated
|
|
images. The flag
|
|
<literal>restrict_isolated_hosts_to_isolated_images</literal>
|
|
can be used to force isolated hosts to only run
|
|
isolated images.</para>
|
|
<para>The admin must specify the isolated set of images
|
|
and hosts in the <filename>nova.conf</filename> file
|
|
using the <literal>isolated_hosts</literal> and
|
|
<literal>isolated_images</literal> configuration
|
|
options. For example:
|
|
<programlisting language="ini">isolated_hosts=server1,server2
|
|
isolated_images=342b492c-128f-4a42-8d3a-c5088cf27d13,ebd267a6-ca86-4d6c-9a0e-bd132d6b7d09</programlisting>
|
|
</para>
|
|
</section>
|
|
<section xml:id="jsonfilter">
|
|
<title>JsonFilter</title>
|
|
<para>The JsonFilter allows a user to construct a custom
|
|
filter by passing a scheduler hint in JSON format. The
|
|
following operators are supported:<itemizedlist>
|
|
<listitem>
|
|
<para>=</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para><</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>></para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>in</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para><=</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>>=</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>not</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>or</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>and</para>
|
|
</listitem>
|
|
</itemizedlist>The filter supports the following variables:<itemizedlist>
|
|
<listitem>
|
|
<para>$free_ram_mb</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>$free_disk_mb</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>$total_usable_ram_mb</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>$vcpus_total</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>$vcpus_used</para>
|
|
</listitem>
|
|
</itemizedlist>Using the <command>nova</command>
|
|
command-line tool, use the <literal>--hint</literal>
|
|
flag:</para>
|
|
<screen><prompt>$</prompt> <userinput>nova boot --image 827d564a-e636-4fc4-a376-d36f7ebe1747 \
|
|
--flavor 1 --hint query='[">=","$free_ram_mb",1024]' server1</userinput></screen>
|
|
<para>With the API, use the
|
|
<literal>os:scheduler_hints</literal> key:</para>
|
|
<programlisting language="json"><xi:include href="../../common/samples/server-scheduler-hints2.json" parse="text"/></programlisting>
|
|
</section>
|
|
<section xml:id="ramfilter">
|
|
<title>RamFilter</title>
|
|
<para>Only schedule instances on hosts that have
|
|
sufficient RAM available. If this filter is not set,
|
|
the scheduler may over provision a host based on RAM
|
|
(for example, the RAM allocated by virtual machine
|
|
instances may exceed the physical RAM).</para>
|
|
<para>This filter can be configured to allow a fixed
|
|
amount of RAM overcommitment by using the
|
|
<literal>ram_allocation_ratio</literal>
|
|
configuration option in
|
|
<filename>nova.conf</filename>. The default setting
|
|
is:</para>
|
|
<programlisting
|
|
language="ini">ram_allocation_ratio=1.5</programlisting>
|
|
<para>This setting enables 1.5 GB instances to run on
|
|
any compute node with 1 GB of free RAM.</para>
|
|
</section>
|
|
<section xml:id="retryfilter">
|
|
<title>RetryFilter</title>
|
|
<para>Filter out hosts that have already been attempted
|
|
for scheduling purposes. If the scheduler selects a
|
|
host to respond to a service request, and the host
|
|
fails to respond to the request, this filter prevents
|
|
the scheduler from retrying that host for the service
|
|
request.</para>
|
|
<para>This filter is only useful if the
|
|
<literal>scheduler_max_attempts</literal>
|
|
configuration option is set to a value greater than
|
|
zero.</para>
|
|
</section>
|
|
<section xml:id="samehostfilter">
|
|
<title>SameHostFilter</title>
|
|
<para>Schedule the instance on the same host as another
|
|
instance in a set of instances. To take advantage of
|
|
this filter, the requester must pass a scheduler hint,
|
|
using <literal>same_host</literal> as the key and a
|
|
list of instance uuids as the value. This filter is
|
|
the opposite of the
|
|
<literal>DifferentHostFilter</literal>. Using the
|
|
<command>nova</command> command-line tool, use the
|
|
<literal>--hint</literal> flag:</para>
|
|
<screen><prompt>$</prompt> <userinput>nova boot --image cedef40a-ed67-4d10-800e-17455edce175 --flavor 1 \
|
|
--hint same_host=a0cf03a5-d921-4877-bb5c-86d26cf818e1 \
|
|
--hint same_host=8c19174f-4220-44f0-824a-cd1eeef10287 server-1</userinput></screen>
|
|
<para>With the API, use the
|
|
<literal>os:scheduler_hints</literal> key:</para>
|
|
<programlisting language="json"><xi:include href="../../common/samples/server-scheduler-hints3.json" parse="text"/></programlisting>
|
|
</section>
|
|
<section xml:id="simplecidraffinityfilter">
|
|
<title>SimpleCIDRAffinityFilter</title>
|
|
<para>Schedule the instance based on host IP subnet range.
|
|
To take advantage of this filter, the requester must
|
|
specify a range of valid IP address in CIDR format, by
|
|
passing two scheduler hints:</para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><literal>build_near_host_ip</literal></term>
|
|
<listitem>
|
|
<para>The first IP address in the subnet (for
|
|
example,
|
|
<literal>192.168.1.1</literal>)</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><literal>cidr</literal></term>
|
|
<listitem>
|
|
<para>The CIDR that corresponds to the subnet
|
|
(for example,
|
|
<literal>/24</literal>)</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
<para>Using the <command>nova</command> command-line tool,
|
|
use the <literal>--hint</literal> flag. For example,
|
|
to specify the IP subnet
|
|
<literal>192.168.1.1/24</literal></para>
|
|
<screen><prompt>$</prompt> <userinput>nova boot --image cedef40a-ed67-4d10-800e-17455edce175 --flavor 1 \
|
|
--hint build_near_host_ip=192.168.1.1 --hint cidr=/24 server-1</userinput></screen>
|
|
<para>With the API, use the
|
|
<literal>os:scheduler_hints</literal> key:</para>
|
|
<programlisting language="json"><xi:include href="../../common/samples/server-scheduler-hints4.json" parse="text"/></programlisting>
|
|
</section>
|
|
</section>
|
|
<section xml:id="weights">
|
|
<title>Weights</title>
|
|
<?dbhtml stop-chunking?>
|
|
<para>When resourcing instances, the Filter Scheduler filters and weighs each host in the
|
|
list of acceptable hosts. Each time the scheduler selects a host, it virtually consumes
|
|
resources on it, and subsequent selections are adjusted accordingly. This process is
|
|
useful when the customer asks for the same large amount of instances, because weight is
|
|
computed for each requested instance.</para>
|
|
<para>All weights are normalized before being summed up; the host with the largest weight is
|
|
given the highest priority.</para>
|
|
<figure xml:id="figure_weighing-hosts">
|
|
<title>Weighing hosts</title>
|
|
<mediaobject>
|
|
<imageobject>
|
|
<imagedata fileref="../../common/figures/nova-weighting-hosts.png"/>
|
|
</imageobject>
|
|
</mediaobject>
|
|
</figure>
|
|
<para>If cells are used, cells are weighted by the scheduler in the same manner as hosts.</para>
|
|
<para>Hosts and cells are weighed based on the following options in the
|
|
<filename>/etc/nova/nova.conf</filename> file:</para>
|
|
<table rules="all" xml:id="table_host-weighting-options">
|
|
<caption>Host Weighting options</caption>
|
|
<col width="10%" title="Section"/>
|
|
<col width="25%" title="Option"/>
|
|
<col width="60%" title="Description"/>
|
|
<thead>
|
|
<tr>
|
|
<th>Section</th>
|
|
<th>Option</th>
|
|
<th>Description</th>
|
|
</tr>
|
|
</thead>
|
|
<tbody>
|
|
<tr valign="top">
|
|
<td>[DEFAULT]</td>
|
|
<td><literal>ram_weight_multiplier</literal></td>
|
|
<td>By default, the scheduler spreads instances across all hosts evenly. Set the
|
|
<option>ram_weight_multiplier</option> option to
|
|
a negative number if you prefer stacking instead of spreading. Use a
|
|
floating-point value.</td>
|
|
</tr>
|
|
<tr valign="top">
|
|
<td>[DEFAULT]</td>
|
|
<td><literal>scheduler_host_subset_size</literal></td>
|
|
<td>New instances are scheduled on a host that is chosen randomly from a subset
|
|
of the N best hosts. This property defines the subset size from which a host
|
|
is chosen. A value of 1 chooses the first host returned by the weighing
|
|
functions.This value must be at least 1. A value less than 1 is ignored, and
|
|
1 is used instead. Use an integer value.</td>
|
|
</tr>
|
|
<tr valign="top">
|
|
<td>[DEFAULT]</td>
|
|
<td><literal>scheduler_weight_classes</literal></td>
|
|
<td>Defaults to <literal>nova.scheduler.weights.all_weighers</literal>, which
|
|
selects the only available weigher, the RamWeigher. Hosts are then weighed
|
|
and sorted with the largest weight winning.</td>
|
|
</tr>
|
|
<tr valign="top">
|
|
<td>[metrics]</td>
|
|
<td><literal>weight_multiplier</literal></td>
|
|
<td>Multiplier for weighing metrices. Use a floating-point value.</td>
|
|
</tr>
|
|
<tr valign="top">
|
|
<td>[metrics]</td>
|
|
<td><literal>weight_setting</literal></td>
|
|
<td>Determines how metrics are weighed. Use a comma-separated list of
|
|
metricName=ratio. For example: "name1=1.0, name2=-1.0" results in:
|
|
<literal>name1.value * 1.0 + name2.value * -1.0</literal>
|
|
</td>
|
|
</tr>
|
|
<tr valign="top">
|
|
<td>[metrics]</td>
|
|
<td><literal>required</literal></td>
|
|
<td><para>Specifies how to treat unavailable metrics:<itemizedlist>
|
|
<listitem><para>True—Raises an exception. To avoid the raised exception, you should use the scheduler
|
|
filter <literal>MetricFilter</literal> to filter out hosts
|
|
with unavailable metrics.</para></listitem>
|
|
<listitem><para>False—Treated as a negative factor in the weighing process (uses the
|
|
<option>weight_of_unavailable</option> option).</para></listitem>
|
|
</itemizedlist></para></td>
|
|
</tr>
|
|
<tr valign="top">
|
|
<td>[metrics]</td>
|
|
<td><literal>weight_of_unavailable</literal></td>
|
|
<td>If <option>required</option> is set to False, and any one of the metrics set
|
|
by <option>weight_setting</option> is unavailable, the
|
|
<option>weight_of_unavailable</option> value is returned to the
|
|
scheduler.</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<para>For example:</para>
|
|
<programlisting language="ini">[DEFAULT]
|
|
scheduler_host_subset_size=1
|
|
scheduler_weight_classes=nova.scheduler.weights.all_weighers
|
|
ram_weight_multiplier=1.0
|
|
[metrics]
|
|
weight_multiplier=1.0
|
|
weight_setting=name1=1.0, name2=-1.0
|
|
required=false
|
|
weight_of_unavailable=-10000.0</programlisting>
|
|
<table rules="all" xml:id="table_cell-weighting-options">
|
|
<caption>Cell weighting options</caption>
|
|
<col width="10%" title="Section"/>
|
|
<col width="25%" title="Option"/>
|
|
<col width="60%" title="Description"/>
|
|
<thead>
|
|
<tr>
|
|
<th>Section</th>
|
|
<th>Option</th>
|
|
<th>Description</th>
|
|
</tr>
|
|
</thead>
|
|
<tbody>
|
|
<tr valign="top">
|
|
<td>[cells]</td>
|
|
<td><literal>mute_weight_multiplier</literal></td>
|
|
<td>Multiplier to weigh mute children (hosts which have not sent capacity or
|
|
capacity updates for some time). Use a negative, floating-point value.</td>
|
|
</tr>
|
|
<tr valign="top">
|
|
<td>[cells]</td>
|
|
<td><literal>mute_weight_value</literal></td>
|
|
<td>Weight value assigned to mute children. Use a positive, floating-point value
|
|
with a maximum of '1.0'.</td>
|
|
</tr>
|
|
<tr valign="top">
|
|
<td>[cells]</td>
|
|
<td><literal>offset_weight_multiplier</literal></td>
|
|
<td>Multiplier to weigh cells, so you can specify a preferred cell. Use a floating
|
|
point value.</td>
|
|
</tr>
|
|
<tr valign="top">
|
|
<td>[cells]</td>
|
|
<td><literal>ram_weight_multiplier</literal></td>
|
|
<td>By default, the scheduler spreads instances across all cells evenly. Set the
|
|
<option>ram_weight_multiplier</option> option to a negative number if
|
|
you prefer stacking instead of spreading. Use a floating-point value.</td>
|
|
</tr>
|
|
<tr valign="top">
|
|
<td>[cells]</td>
|
|
<td><literal>scheduler_weight_classes</literal></td>
|
|
<td>Defaults to <literal>nova.cells.weights.all_weighers</literal>, which maps to
|
|
all cell weighers included with Compute. Cells are then weighed and sorted
|
|
with the largest weight winning.</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<para>For example:</para>
|
|
<programlisting language="ini">[cells]
|
|
scheduler_weight_classes=nova.cells.weights.all_weighers
|
|
mute_weight_multiplier=-10.0
|
|
mute_weight_value=1000.0
|
|
ram_weight_multiplier=1.0
|
|
offset_weight_multiplier=1.0</programlisting>
|
|
</section>
|
|
<section xml:id="chance-scheduler">
|
|
<title>Chance scheduler</title>
|
|
<?dbhtml stop-chunking?>
|
|
<para>As an administrator, you work with the Filter Scheduler.
|
|
However, the Compute service also uses the Chance
|
|
Scheduler,
|
|
<literal>nova.scheduler.chance.ChanceScheduler</literal>,
|
|
which randomly selects from lists of filtered
|
|
hosts.</para>
|
|
</section>
|
|
<xi:include
|
|
href="../../common/section_cli_nova_host_aggregates.xml"/>
|
|
<section xml:id="compute-scheduler-config-ref">
|
|
<title>Configuration reference</title>
|
|
<para>To customize the Compute scheduler, use the configuration option
|
|
settings documented in <xref
|
|
linkend="config_table_nova_scheduling"/>.</para>
|
|
</section>
|
|
</section>
|