Ceph health reports PG_DAMAGED after a failed disk or node replacement

After adding a new OSD node on a compact cluster, Ceph health may report HEALTH_ERR with the ceph health detail command output containing PG_DAMAGED and OSD_SCRUB_ERRORS messages. For example:

$ ceph -s

cluster:
 id:     8bca9dfb-df99-4920-bba0-e5bca59876b4
 health: HEALTH_ERR
         1 scrub errors
         Possible data damage: 1 pg inconsistent

services:
 mon: 3 daemons, quorum a,b,c (age 3h)
 mgr: a(active, since 3h), standbys: b
 osd: 4 osds: 4 up (since 109m), 4 in (since 110m)
 rgw: 2 daemons active (2 hosts, 1 zones)

$ ceph health detail

HEALTH_ERR 1 scrub errors; Possible data damage: 1 pg inconsistent
[ERR] OSD_SCRUB_ERRORS: 1 scrub errors
[ERR] PG_DAMAGED: Possible data damage: 1 pg inconsistent
    pg 11.2a is active+clean+inconsistent, acting [3,1]

To fix the PG_DAMAGED health error:

1. Obtain the damaged placement group (PG) ID:

   ceph health detail
   

   Example of system response:

   HEALTH_ERR 1 scrub errors; Possible data damage: 1 pg inconsistent
   [ERR] OSD_SCRUB_ERRORS: 1 scrub errors
   [ERR] PG_DAMAGED: Possible data damage: 1 pg inconsistent
       pg 11.2a is active+clean+inconsistent, acting [3,1]
   

   In the example above, 11.2a is the required PG ID.

2. Repair the damaged PG:

   ceph pg repair <pgid>
   

   Substitute <pgid> with a damaged PG ID. For example:

   ceph pg repair 11.2a