0x1a / ceph_safe_disk

Ceph disk removal safety

ceph-safe-disk

Ceph disk safety removal tool

Building

Builds on stable rustc as of 1.8

Using

ceph-safe-disk checks whether OSDs in a ceph cluster are removable or not. This is done in two ways, the quick way, and the more exhaustive way.

Usage: ceph-safe-disk [OPTION]

Options:
    -h, --help          Print help information
    -q, --quick         Give a quick, non-exhaustive status of removable OSDs
    -e, --exhaustive    Give an exhaustive status of removable OSDs

Exit statuses:
    0: Safe to remove an OSD
    1: Not safe to remove an OSD
    2: General error

Quick

The quick option -q checks whether the cluster's minimum OSD size is satisfied (that is the current size is min_size + 1). This could be unsafe as a placement group might not be reproduced.

Exhaustive

The more exhaustive option -e maps out placement groups to OSDs and then checks the safety of each individual OSD. If a placement group is marked unsafe then the OSD is marked unsafe as well. This is done for each OSD in a placement group's acting OSD list.

A Note on Timing

The timing of this tool depends on when ceph reports the status of OSDs. More information can be found on the ceph documentation page here.

Safety

ceph-safe-disk marks OSDs in the following states: Pending, Removable, and Not removable. Removable for an OSD being asbolutely safe to remove, Not removable for an OSD that is unsafe to remove, and Pending for an OSD that's safety cannot be guarenteed.

The only state for a placement group marked as absolutely safe is active+clean. Some liberty was taken as to what is regarded as safe, unsafe, and pending.

PG states that currently immediately result in unsafe are:

• backfill
• backfill-toofull
• wait-backfill
• down
• undersized
• incomplete

Any other state is marked as Pending.