openstack
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nova
Code Issues Proposed changes

Note the aggregate allocation ratio restriction in scheduler docs 

This borrows from the release note in change
I01f20f275bbd5451ace5c1e6f41ab38d488dae4e to document the
regression, introduced in Ocata, where allocation ratio settings
in the aggregate core/ram/disk filters are not honored because
of placement being used by the FilterScheduler.

While there is related work going on around this in
blueprint initial-allocation-ratios and
blueprint placement-aggregate-allocation-ratios, it is still
a limitation in the current code base and needs to be called
out in the docs.

Change-Id: Ifaf596a8572637f843f47daf5adce394b0365676
Related-Bug: #1804125
(cherry picked from commit d65c18a0a9)
This commit is contained in:
Matt Riedemann 2018-11-28 17:07:11 -05:00
parent f3a0b89efd
commit 899b4ca5a2
1 changed files with 24 additions and 0 deletions
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doc/source/admin/configuration/schedulers.rst
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@ -114,6 +114,8 @@ global setting. If the host is in more than one aggregate and more than one
value is found, the minimum value will be used. For information about how to
use this filter, see :ref:`host-aggregates`. See also :ref:`CoreFilter`.
Note the ``cpu_allocation_ratio`` :ref:`bug 1804125 <bug-1804125>` restriction.
AggregateDiskFilter
-------------------
@ -123,6 +125,9 @@ global setting. If the host is in more than one aggregate and more than one
value is found, the minimum value will be used. For information about how to
use this filter, see :ref:`host-aggregates`. See also :ref:`DiskFilter`.
Note the ``disk_allocation_ratio`` :ref:`bug 1804125 <bug-1804125>`
restriction.
AggregateImagePropertiesIsolation
---------------------------------
@ -249,6 +254,8 @@ aggregate and thus more than one value is found, the minimum value will be
used. For information about how to use this filter, see
:ref:`host-aggregates`. See also :ref:`ramfilter`.
Note the ``ram_allocation_ratio`` :ref:`bug 1804125 <bug-1804125>` restriction.
AggregateTypeAffinityFilter
---------------------------
@ -1063,6 +1070,23 @@ as well as the other filters that are typically enabled:
scheduler_default_filters=AggregateInstanceExtraSpecsFilter,RetryFilter,AvailabilityZoneFilter,ComputeCapabilitiesFilter,ImagePropertiesFilter,ServerGroupAntiAffinityFilter,ServerGroupAffinityFilter
.. _bug-1804125:
.. note:: Regarding the `AggregateCoreFilter`_, `AggregateDiskFilter`_ and
`AggregateRamFilter`_, starting in 15.0.0 (Ocata) there is a behavior
change where aggregate-based overcommit ratios will no longer be honored
during scheduling for the FilterScheduler. Instead, overcommit values must
be set on a per-compute-node basis in the Nova configuration files.
If you have been relying on per-aggregate overcommit, during your upgrade,
you must change to using per-compute-node overcommit ratios in order for
your scheduling behavior to stay consistent. Otherwise, you may notice
increased NoValidHost scheduling failures as the aggregate-based overcommit
is no longer being considered.
See `bug 1804125 <https://bugs.launchpad.net/nova/+bug/1804125>`_ for more
details.
Example: Specify compute hosts with SSDs
----------------------------------------