From d65c18a0a9f02e6d37f2b87ff61f1740c8bfc867 Mon Sep 17 00:00:00 2001 From: Matt Riedemann Date: Wed, 28 Nov 2018 17:07:11 -0500 Subject: [PATCH] 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 --- doc/source/admin/configuration/schedulers.rst | 24 +++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/doc/source/admin/configuration/schedulers.rst b/doc/source/admin/configuration/schedulers.rst index b3388e89fcce..6df9951149ad 100644 --- a/doc/source/admin/configuration/schedulers.rst +++ b/doc/source/admin/configuration/schedulers.rst @@ -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 ` 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 ` +restriction. + AggregateImagePropertiesIsolation --------------------------------- @@ -255,6 +260,8 @@ 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 ` restriction. + AggregateTypeAffinityFilter --------------------------- @@ -1088,6 +1095,23 @@ as well as the other filters that are typically enabled: [filter_scheduler] enabled_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 `_ for more + details. + Example: Specify compute hosts with SSDs ----------------------------------------