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62 lines
2.4 KiB
ReStructuredText
62 lines
2.4 KiB
ReStructuredText
===============================================
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Affinity/Anti Affinity of instances in a groups
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===============================================
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This task can be divided into two separate parts. First is a change of behavior
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of host aggregates, to be able to include ironic nodes. Second, involves
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changes to the scheduler to support spreading instances across various groups.
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Questions
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---------
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There are several ways that aggregate (anti)affinity could be defined
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expressed.
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#. Pass through hints, both information about server group and condition for
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server placement against host aggregates:
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.. code:: shell-session
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openstack aggregate-create rack1
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openstack aggregate-create rack2
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openstack aggregate-set-metadata rack1 rack=1
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openstack aggregate-set-metadata rack2 rack=1
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openstack aggregate-add-host rack1 <UUID of Ironic node A>
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openstack aggregate-add-host rack2 <UUID of Ironic node B>
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openstack server-group-create not-same-rack anti-affinity
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openstack server create --image=IMAGE_ID --flavor=1 \
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--hint group=not-same-rack --hint property=rack
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#. Implement own policies to set on instance groups, like
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``rack_antiaffinity``, ``pz_antiaffinity`` etc, and than during boot time
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just pass a server group name. For instance:
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.. code:: shell-session
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openstack aggregate-create rack1
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openstack aggregate-create rack2
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openstack aggregate-set-metadata rack1 rack=1
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openstack aggregate-set-metadata rack2 rack=1
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openstack aggregate-add-host rack1 <UUID of Ironic node A>
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openstack aggregate-add-host rack2 <UUID of Ironic node B>
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openstack server-group-create not-same-rack rack-anti-affinity
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openstack server create --image=IMAGE_ID --flavor=1 \
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--hint group=not-same-rack
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#. Hardcode policy into the server group name, but this requires from users, to
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be very strict about naming of server groups:
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.. code:: shell-session
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openstack aggregate-create rack1
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openstack aggregate-create rack2
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openstack aggregate-set-metadata rack1 rack=1
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openstack aggregate-set-metadata rack2 rack=1
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openstack aggregate-add-host rack1 <UUID of Ironic node A>
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openstack aggregate-add-host rack2 <UUID of Ironic node B>
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openstack server-group-create rack-<unique-name> anti-affinity
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openstack server create --image=IMAGE_ID --flavor=1 \
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--hint group=rack-<unique-name>
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Which solution should we take?
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