Alert rule: CephMonDiskspaceLow

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The space available to a monitor’s store is approaching full (>70% is the default). You should increase the space available to the monitor(s). The monitor’s store can be found at /var/lib/rook/<MON_NAME>/data on the host.

Look for old, rotated versions of .log and MANIFEST. IMPORTANT: Don’t touch any *.sst files. Also check any other directories under /var/lib/rook and other directories on the same filesystem, often /var/log and /var/tmp are culprits.

Steps for debugging

Check node low on disk space

$ ceph_cluster_ns=syn-rook-ceph-cluster
$ ceph_mon_name=a (1)
$ kubectl -n ${ceph_cluster_ns} get deploy -lapp=rook-ceph-mon,mon=${ceph_mon_name}  -ojson | jq '.items[].spec.template.spec.nodeSelector'
  "": "storage-XXXX" (2)
1 The name of the monitor that’s alerting.
2 The node that the monitor is running on.

Increase the size of the node’s disk

Increase the size of the node’s disk according to your cloud provider’s documentation.