[Bug 1704106] Please test proposed package

[Corey Bryant]

Hello Arne, or anyone else affected,

Accepted cinder into ocata-proposed. The package will build now and be
available in the Ubuntu Cloud Archive in a few hours, and then in the
-proposed repository.

Please help us by testing this new package. To enable the -proposed
repository:

  sudo add-apt-repository cloud-archive:ocata-proposed
  sudo apt-get update

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, and change the tag
from verification-ocata-needed to verification-ocata-done. If it does
not fix the bug for you, please add a comment stating that, and change
the tag to verification-ocata-failed. In either case, details of your
testing will help us make a better decision.

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

** Changed in: cloud-archive/ocata
       Status: Triaged => Fix Committed

** Tags added: verification-ocata-needed

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https://bugs.launchpad.net/bugs/1704106

Title:
  [SRU] Gathering of thin provisioning stats breaks c-vol

Status in Cinder:
  Fix Released
Status in Ubuntu Cloud Archive:
  Fix Released
Status in Ubuntu Cloud Archive ocata series:
  Fix Committed
Status in Ubuntu Cloud Archive pike series:
  Triaged

Bug description:
  [Impact]

  Backport config option added in Queens to allow disabling the
  collection of stats from all rbd volumes since this causes
  tons of non-fatal race conditions and slows down deletes to
  the point where the rpc thread pool fills up blocking further
  requests. Our charms do not configure pool by default and we
  are not aware of anyone doing this in the field so this patch
  enables this option by default.

  [Test Case]

  By default no change in behaviour should occur. To test the
  new feature we need to enable it i.e.:

  * deploy openstack ocata
  * set rbd_exclusive_cinder_pool = true in cinder.conf
  * create 100 volumes via cinder
  * also create 100 volumes from the cinder pool but using the rbd client directly
  * delete cinder volumes (via cinder) and delete the non-cinder rbd volumes using rbd client
  * ensure there are no exceptions in cinder-volume.log

  [Regression Potential]
  The default behaviour is unchanged so no regression is expected.

  ==========================================================================

  The gathering of the thin provisioning stats is done by looping over
  all volumes:

  https://github.com/openstack/cinder/blob/master/cinder/volume/drivers/rbd.py#L369

  For larger deployments, this loop (done at start-up, upon volume
  deletion and as periodic a task) is taking too long and hence breaks
  the c-vol service.

  From what I understand, the overall idea of this stats gathering is to
  bring the current real fill status of the pool to the admin's
  attention in case over-subscription was configured. For this, a fill
  status at the pool level (rather than the volume level) should be good
  enough.

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