Ceph: Designing and Implementing Scalable Storage Systems

Monitoring Ceph MDS

Ceph MDS servers manage CephFS filesystems. A Ceph MDS server can be in various states including up, down, active, and inactive. An MDS server should always be up and active when it is in a correct and functioning state.

There are two main commands we can use to monitor an operational MDS cluster. We use mds stat to get a quick insight into the present state of MDSs. You might recognize this output format as the same one presented by the Ceph status fsmap key.

root@ceph-client0:~# ceph mds state38611: 1/1/1 up {0=ceph-mds0=up:active}

If we would like the detailed output of the MDS map of a given cluster, we can use the mds dump subcommand. Like all other subcommands containing dump, it prints the entire MDS map, which ...