Alert rule: CephFilesystemDegraded

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One or more metadata daemons (MDS ranks) are failed or in a damaged state. At best the filesystem is partially available, worst case is the filesystem is completely unusable.

Steps for debugging

Check for damaged metadata

  1. List pools with damaged metadata

    $ ceph_cluster_ns=syn-rook-ceph-cluster
    $ kubectl -n ${ceph_cluster_ns} exec -it deploy/rook-ceph-tools -- ceph mds metadata
  2. Check for damaged metadata in the mds admin socket

    # Find the mds daemon pod
    $ ceph_cluster_ns=syn-rook-ceph-cluster
    $ damaged_fspool=<FSPOOL> # e.g. fspool-a
    $ kubectl -n ${ceph_cluster_ns} get pods | grep ceph-mds | grep ${damaged_fspool}
    # Query the mds admin socket for damaged metadata
    $ ka -n ${ceph_cluster_ns} exec -it <POD> -- ceph daemon /var/run/ceph/ceph-mds.fspool-a.asok damage ls