charm pause/resume actions removes the OSD, rather than just stoping a service

[Chris MacNaughton]

Per Ceph's documentation, 'down'ing the OSD will cause the ceph cluster to start rebalancing the cluter (http://docs.ceph.com/docs/master/rados/operations/add-or-rm-osds/#take-the-osd-out-of-the-cluster); it is surprising that `pause` would cause ceph to start a rebalance.

[David Ames (thedac)]

We should rename the pause and resume actions.

Possibly extend the existing code to take a single osd out at a time.
Or possibly remove entirely.

[Felipe Reyes (freyes)]

Considering the charm deployment guide has a section where it describes an upgrade of the charms using pause/resume ( https://docs.openstack.org/project-deploy-guide/charm-deployment-guide/latest/app-upgrade-openstack.html#ha-with-pause-resume ), I think we should reconsider this bug's importance.

Last week I was dragged to a live session where the user was upgrading their env using that guide (which led to bug 1802917).

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/620175

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/620175
Committed: https://git.openstack.org/cgit/openstack/charm-ceph-osd/commit/?id=1e0c6548b886fba21055feb16396ac2ad13da7a8
Submitter: Zuul
Branch: master

commit 1e0c6548b886fba21055feb16396ac2ad13da7a8
Author: David Ames <email address hidden>
Date: Mon Nov 26 14:40:48 2018 -0800

    Rename pause/resume osd-out/osd-in

    The actions pause and resume actually take all osds on a unit out of the
    cluster. This is incredibly misleading.

    This change renames to osd-out and osd-in to better describe what the
    actions actually do.

    Change-Id: I76793999f5d3382563eff308a5d7c4db18d065a0
    Closes-Bug: #1793507

[Felipe Reyes (freyes)]

David, do you have plans on backporting this change?, I understand that due to the nature of the patch may not be a good idea to backport it, on the other hand the idea of having a potential non desired rebalance not good either.