50 lines
2.8 KiB
YAML
50 lines
2.8 KiB
YAML
upgrade:
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- |
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It is now possible to count quota usage for cores and ram from the
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placement service and instances from instance mappings in the API database
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instead of counting resources from cell databases. This makes quota usage
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counting resilient in the presence of down or poor-performing cells.
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Quota usage counting from placement is opt-in via the
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``[quota]count_usage_from_placement`` configuration option.
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There are some things to note when opting in to counting quota usage from
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placement:
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* Counted usage will not be accurate in an environment where multiple Nova
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deployments are sharing a placement deployment because currently
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placement has no way of partitioning resource providers between different
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Nova deployments. Operators who are running multiple Nova deployments
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that share a placement deployment should not set the
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``[quota]count_usage_from_placement`` configuration option to ``True``.
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* Behavior will be different for resizes. During a resize, resource
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allocations are held on both the source and destination (even on the same
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host, see https://bugs.launchpad.net/nova/+bug/1790204) until the resize
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is confirmed or reverted. Quota usage will be inflated for servers in
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the ``VERIFY_RESIZE`` state and operators should weigh the advantages and
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disadvantages before enabling ``[quota]count_usage_from_placement``.
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* The ``populate_queued_for_delete`` and ``populate_user_id`` online data
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migrations must be completed before usage can be counted from placement.
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Until the data migration is complete, the system will fall back to legacy
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quota usage counting from cell databases depending on the result of an
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``EXISTS`` database query during each quota check, if
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``[quota]count_usage_from_placement`` is set to ``True``. Operators who
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want to avoid the performance hit from the ``EXISTS`` queries should wait
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to set the ``[quota]count_usage_from_placement`` configuration option to
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``True`` until after they have completed their online data migrations via
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``nova-manage db online_data_migrations``.
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* Behavior will be different for unscheduled servers in ``ERROR`` state.
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A server in ``ERROR`` state that has never been scheduled to a compute
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host will not have placement allocations, so it will not consume quota
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usage for cores and ram.
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* Behavior will be different for servers in ``SHELVED_OFFLOADED`` state.
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A server in ``SHELVED_OFFLOADED`` state will not have placement
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allocations, so it will not consume quota usage for cores and ram. Note
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that because of this, it will be possible for a request to unshelve a
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server to be rejected if the user does not have enough quota available to
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support the cores and ram needed by the server to be unshelved.
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