ceph/doc/rados/configuration
Sridhar Seshasayee a34fc8875b common/options: Change HDD OSD shard configuration defaults for mClock
Based on tests performed at scale on a HDD based cluster, it was found
that scheduling with mClock was not optimal with multiple OSD shards. For
e.g., in the scaled cluster with multiple OSD node failures, the client
throughput was found to be inconsistent across test runs coupled with
multiple reported slow requests.

However, the same test with a single OSD shard and with multiple worker
threads yielded significantly better results in terms of consistency of
client and recovery throughput across multiple test runs.

For more details see https://tracker.ceph.com/issues/66289.

Therefore, as an interim measure until the issue with multiple OSD shards
(or multiple mClock queues per OSD) is investigated and fixed, the
following change to the default HDD OSD shard configuration is made:

 - osd_op_num_shards_hdd = 1 (was 5)
 - osd_op_num_threads_per_shard_hdd = 5 (was 1)

The other changes in this commit include:
 - Doc change to the OSD and mClock config reference describing
   this change.
 - OSD troubleshooting entry on the procedure to change the shard
   configuration for clusters affected by this issue running on older
   releases.
 - Add release note for this change.

Fixes: https://tracker.ceph.com/issues/66289
Signed-off-by: Sridhar Seshasayee <sseshasa@redhat.com>
(cherry picked from commit 0d81e72137)

Conflicts:
        doc/rados/troubleshooting/troubleshooting-osd.rst
- Included the troubleshooting entry before the "Flapping OSDs" section.
        PendingReleaseNotes
- Moved the release note under 18.2.4 section and removed unrelated entries
2024-11-28 14:08:00 +05:30
..
auth-config-ref.rst doc/rados/config: edit auth-config-ref 2023-04-09 12:24:00 +10:00
bluestore-config-ref.rst doc/rados/configuration/bluestore-config-ref: Fix lowcase typo 2023-11-29 00:41:44 +07:00
ceph-conf.rst doc/config: edit "ceph-conf.rst" 2023-11-13 00:01:29 +10:00
common.rst doc/rados: update common.rst 2024-03-19 03:41:00 +10:00
demo-ceph.conf doc: account for PG autoscaling being the default 2023-04-17 23:00:46 +02:00
filestore-config-ref.rst doc/rados: remove FileStore material (in Reef) 2023-10-14 06:19:44 +10:00
general-config-ref.rst doc/rados/configuration/general-config-ref: use describe to define non-options 2021-05-06 22:21:43 +08:00
index.rst doc/rados: fix grammar in configuration/index.rst 2022-11-15 08:37:05 +10:00
journal-ref.rst docs: warning and remove few docs section for Filestore 2023-04-20 07:44:32 +02:00
mclock-config-ref.rst common/options: Change HDD OSD shard configuration defaults for mClock 2024-11-28 14:08:00 +05:30
mon-config-ref.rst doc: s/Whereas,/Although/ 2024-11-02 13:05:12 +10:00
mon-lookup-dns.rst doc/rados: add link to messenger v2 info in mon-lookup-dns.rst 2024-09-15 20:49:35 +10:00
mon-osd-interaction.rst doc: Fix many spelling errors 2022-07-02 23:38:18 -04:00
msgr2.rst doc/rados: remove dual-stack docs 2024-04-24 21:52:09 +10:00
network-config-ref.rst doc/rados: add options to network config ref 2024-06-07 03:22:40 +10:00
osd-config-ref.rst common/options: Change HDD OSD shard configuration defaults for mClock 2024-11-28 14:08:00 +05:30
pool-pg-config-ref.rst doc/rados: update config for autoscaler 2024-02-04 08:26:25 +10:00
pool-pg.conf doc: account for PG autoscaling being the default 2023-04-17 23:00:46 +02:00
storage-devices.rst doc/rados: edit filestore-config-ref.rst 2023-05-25 18:48:59 +10:00