ceph/doc/rados/operations/pg-states.rst

========================
 Placement Group States
========================

When checking a cluster's status (e.g., running ``ceph -w`` or ``ceph -s``), 
Ceph will report on the status of the placement groups. A placement group has 
one or more states. The optimum state for placement groups in the placement group
map is ``active + clean``. 

*Creating*
  Ceph is still creating the placement group.

*Active*
  Ceph will process requests to the placement group.

*Clean*
  Ceph replicated all objects in the placement group the correct number of times.

*Down*
  A replica with necessary data is down, so the placement group is offline.

*Replay*
  The placement group is waiting for clients to replay operations after an OSD crashed.

*Splitting*
  Ceph is splitting the placement group into multiple placement groups. (functional?)

*Scrubbing*
  Ceph is checking the placement group for inconsistencies.

*Degraded*
  Ceph has not replicated some objects in the placement group the correct number of times yet.

*Inconsistent*
  Ceph detects inconsistencies in the one or more replicas of an object in the placement group
  (e.g. objects are the wrong size, objects are missing from one replica *after* recovery finished, etc.).

*Peering*
  The placement group is undergoing the peering process

*Repair*
  Ceph is checking the placement group and repairing any inconsistencies it finds (if possible).

*Recovering*
  Ceph is migrating/synchronizing objects and their replicas.

*Backfill*
  Ceph is scanning and synchronizing the entire contents of a placement group
  instead of inferring what contents need to be synchronized from the logs of
  recent operations. *Backfill* is a special case of recovery.

*Wait-backfill*
  The placement group is waiting in line to start backfill.

*Backfill-toofull*
  A backfill operation is waiting because the destination OSD is over its
  full ratio.

*Incomplete*
  Ceph detects that a placement group is missing a necessary period of history 
  from its log.  If you see this state, report a bug, and try to start any
  failed OSDs that may contain the needed information.

*Stale*
  The placement group is in an unknown state - the monitors have not received
  an update for it since the placement group mapping changed.

*Remapped*
  The placement group is temporarily mapped to a different set of OSDs from what
  CRUSH specified.