openstack/ironic
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Update Nova configuration documentation

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* Actually explain *why* we change options, instead of merely copy-pasting
  an old version of their description.
* Document the new consecutive_build_service_disable_threshold, which may
  be quite confusing at first.
* Do not force options that are not needed with resource classes.
* Remove excessive indentation from the list.
* Small wording fixes here and there.

Change-Id: Ia60fedb8b28936530b24f5f05a654e083fc67499
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Dmitry Tantsur 2017-08-24 17:59:52 +02:00 committed by Ruby Loo
parent 9daabbbb05
commit 9935093ead
1 changed files with 69 additions and 44 deletions
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113
doc/source/install/configure-compute.rst
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@ -21,68 +21,93 @@ driver. The configuration file for the Compute service is typically located at
The following configuration file must be modified on the Compute
service's controller nodes and compute nodes.
#. Change these configuration options in the ``default`` section, as follows:
#. Change these configuration options in the Compute service configuration
file (for example, ``/etc/nova/nova.conf``):
.. code-block:: ini
[default]
# Driver to use for controlling virtualization. Options
# include: libvirt.LibvirtDriver, xenapi.XenAPIDriver,
# fake.FakeDriver, baremetal.BareMetalDriver,
# vmwareapi.VMwareESXDriver, vmwareapi.VMwareVCDriver (string
# value)
#compute_driver=<None>
# Defines which driver to use for controlling virtualization.
# Enable the ironic virt driver for this compute instance.
compute_driver=ironic.IronicDriver
# Firewall driver (defaults to hypervisor specific iptables
# driver) (string value)
#firewall_driver=<None>
# Firewall driver to use with nova-network service.
# Ironic supports only neutron, so set this to noop.
firewall_driver=nova.virt.firewall.NoopFirewallDriver
# The scheduler host manager class to use (string value)
#scheduler_host_manager=host_manager
scheduler_host_manager=ironic_host_manager
# Virtual ram to physical ram allocation ratio which affects
# all ram filters. This configuration specifies a global ratio
# for RamFilter. For AggregateRamFilter, it will fall back to
# this configuration value if no per-aggregate setting found.
# (floating point value)
#ram_allocation_ratio=1.5
ram_allocation_ratio=1.0
# Amount of disk in MB to reserve for the host (integer value)
#reserved_host_disk_mb=0
# Amount of memory in MB to reserve for the host so that it is always
# available to host processes.
# It is impossible to reserve any memory on bare metal nodes, so set
# this to zero.
reserved_host_memory_mb=0
# Determines if the Scheduler tracks changes to instances to help with
# its filtering decisions (boolean value)
#scheduler_tracks_instance_changes=True
scheduler_tracks_instance_changes=False
[filter_scheduler]
# New instances will be scheduled on a host chosen randomly from a subset
# of the N best hosts, where N is the value set by this option. Valid
# values are 1 or greater. Any value less than one will be treated as 1.
# For ironic, this should be set to a number >= the number of ironic nodes
# to more evenly distribute instances across the nodes.
#scheduler_host_subset_size=1
scheduler_host_subset_size=9999999
# Enables querying of individual hosts for instance information.
# Not possible for bare metal nodes, so set it to False.
track_instance_changes=False
If you have not migrated to using :ref:`scheduling-resource-classes`, then
the following should be set as well:
#. If you have not switched to make use of :ref:`scheduling-resource-classes`,
then the following options should be set as well. They must be removed from
the configuration file after switching to resource classes.
.. code-block:: ini
[default]
[scheduler]
# Flag to decide whether to use baremetal_scheduler_default_filters or not.
# (boolean value)
#scheduler_use_baremetal_filters=False
scheduler_use_baremetal_filters=True
# Use the ironic scheduler host manager. This host manager will consume
# all CPUs, disk space, and RAM from a host as bare metal hosts, can not
# be subdivided into multiple instances. Scheduling based on resource
# classes does not use CPU/disk/RAM, so the default host manager can be
# used in such cases.
host_manager=ironic_host_manager
This option is deprecated and has to be unset after migration
to resource classes.
[filter_scheduler]
# Size of subset of best hosts selected by scheduler.
# New instances will be scheduled on a host chosen randomly from a
# subset of the 999 hosts. The big value is used to avoid race
# conditions, when several instances are scheduled on the same bare
# metal nodes. This is not a problem when resource classes are used.
host_subset_size=999
# This flag enables a different set of scheduler filters, which is more
# suitable for bare metals. CPU, disk and memory filters are replaced
# with their exact counterparts, to make sure only nodes strictly
# matching the flavor are picked. These filters do not work with
# scheduling based on resource classes only.
use_baremetal_filters=True
#. Carefully consider the following option:
.. code-block:: ini
[compute]
# This option will cause nova-compute to set itself to a disabled state
# if a certain number of consecutive build failures occur. This will
# prevent the scheduler from continuing to send builds to a compute
# service that is consistently failing. In the case of bare metal
# provisioning, however, a compute service is rarely the cause of build
# failures. Furthermore, bare metal nodes, managed by a disabled
# compute service, will be remapped to a different one. That may cause
# the second compute service to also be disabled, and so on, until no
# compute services are active.
# If this is not the desired behavior, consider increasing this value or
# setting it to 0 to disable this behavior completely.
#consecutive_build_service_disable_threshold = 10
[scheduler]
# This value controls how often (in seconds) the scheduler should
# attempt to discover new hosts that have been added to cells.
# If negative (the default), no automatic discovery will occur.
# As each bare metal node is represented by a separate host, it has
# to be discovered before the Compute service can deploy on it.
# It can be done manually after enrolling every node or batch of nodes,
# or this periodic task can be enabled to do it automatically.
#discover_hosts_in_cells_interval=-1
#. Change these configuration options in the ``ironic`` section.
Replace: