Comment 2 for bug 1832418

Billy clarified that stopping the OSDs is required because Hammer ran ceph-osd
processes as root. Jewel fixed this security flaw by changing the user to ceph.

The proposed flow for Hammer -> Jewel when an ownership update is required:
    Disable all OSDs [0]
    Update Version
    For each OSD
        Stop OSD
        Fix Ownership
        Enable OSD [1]
        Start OSD
    Enable all OSDs [2]

[0] Systemd: disable all. Upstart: create ceph-osd-all manual override file.
[1] Systemd: enable osd. Upstart: Noop. Individual disable not supported.
[2] Systemd: Noop (already enabled). Upstart: Remove the ceph-osd-all override.

I want to clarify that this bug is tracking two issues:
1. Charm should not modify 'ready' touchfiles.
2. OSDs should be disabled on the leading edge of version updates.

I'm proposing these issues be fixed together because Trusty is not accepting any
updates. By requiring a leading-edge disable, the charm can remove reliance on
the touchfile without making any changes to the ceph upstart config files.