Ceph » mgr

Currently, "cephadm bootstrap" appears to create a pool because "devicehealth", as an "always on" module, gets created when the first MGR is deployed.

The pool actually gets created by mgr/devicehealth, not by cephadm - hence this bug is opened against mgr/devicehealth, even though - from the user's perspective - the problem happens when the "cephadm bootstrap" command is issued.

Because mgr/devicehealth creates a pool before the cluster has any OSDs, the cluster enters HEALTH_WARN immediately after bootstrap:

master:~ # ceph -s
  cluster:
    id:     fed46cbe-d157-11ea-901a-52540084b2ce
    health: HEALTH_WARN
            OSD count 0 < osd_pool_default_size 3

  services:
    mon: 1 daemons, quorum node1 (age 67s)
    mgr: node1.ikkrrt(active, since 39s)
    osd: 0 osds: 0 up, 0 in

  data:
    pools:   1 pools, 1 pgs
    objects: 0 objects, 0 B
    usage:   0 B used, 0 B / 0 B avail
    pgs:     100.000% pgs unknown
             1 unknown

The pool is:

 
master:~ # ceph osd pool ls
device_health_metrics

It seems like the creation of this pool should be linked to deployment of the first OSD, not to the deployment of the first MON/MGR.