[Bug 1909162] Re: cluster log slow request spam

[Łukasz Zemczak]

Hello Dan, or anyone else affected,

Accepted ceph into groovy-proposed. The package will build now and be
available at
https://launchpad.net/ubuntu/+source/ceph/15.2.8-0ubuntu0.20.10.1 in a
few hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.  Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested, what testing has been
performed on the package and change the tag from verification-needed-
groovy to verification-done-groovy. If it does not fix the bug for you,
please add a comment stating that, and change the tag to verification-
failed-groovy. In either case, without details of your testing we will
not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

** Changed in: ceph (Ubuntu Groovy)
       Status: In Progress => Fix Committed

** Tags added: verification-needed verification-needed-groovy

** Changed in: ceph (Ubuntu Focal)
       Status: In Progress => Fix Committed

** Tags added: verification-needed-focal

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https://bugs.launchpad.net/bugs/1909162

Title:
  cluster log slow request spam

Status in Ubuntu Cloud Archive:
  In Progress
Status in Ubuntu Cloud Archive train series:
  In Progress
Status in Ubuntu Cloud Archive ussuri series:
  In Progress
Status in ceph package in Ubuntu:
  In Progress
Status in ceph source package in Focal:
  Fix Committed
Status in ceph source package in Groovy:
  Fix Committed
Status in ceph source package in Hirsute:
  In Progress

Bug description:
  [Impact]

  A recent change (issue#43975 [0]) was made to slow request logging to
  include detail on each operation in the cluster logs. With this
  change, detail for every slow request is always sent to the monitors
  and added to the cluster logs.

  This does not scale. Large, high-throughput clusters can overwhelm
  their monitors with spurious logs in the event of a performance issue.
  Disrupting the monitors can then cause further instability in the
  cluster.

  This SRU reverts the cluster logging of every slow request the osd is
  processing.

  The slow request clog change was added in nautilus (14.2.10) and
  octopus (15.2.0).

  [Test Case]

  Stress the cluster with a benchmarking tool to generate slow requests
  and observe the cluster logs.

  [Where problems could occur]

  The cluster logs contain detailed debug information on slow requests
  that is useful for smaller, low-throughput clusters. While these logs
  are not used by ceph, they may be used by the cluster administrators
  (for monitoring or alerts). Changing this logging behavior may be
  unexpected.

  [Other Info]

  The intent is to re-enable this feature behind a configurable setting,
  but the solution must be discussed upstream.

  The same slow request detail can be enabled for each osd by raising
  the "debug osd" log level to 20.

  [0] https://tracker.ceph.com/issues/43975

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