Adding OSDs

OSDs are added via a new ceph-osd unit. The unit’s underlying machine is understood to house one or more storage devices.

  1. Ensure that the cluster is in a healthy state. On any MON (such as the leader unit here) run a status check:

    juju ssh ceph-mon/leader sudo ceph status
  2. Add a ceph-osd unit:

    juju add-unit ceph-osd

A specific underlying machine (MAAS node) can be chosen via Juju constraints.

  1. If the new unit’s machine has disks that are not listed by the ceph-osd charm’s osd-devices configuration option then the add-disk action should be used to manually add OSD volumes:

    juju run-action --wait ceph-osd/5 add-disk osd-devices=/dev/sde

    Alternatively, update the value of the osd-devices option:

    juju config ceph-osd osd-devices='/dev/sdb /dev/sdc /dev/sde'

An existing OSD cannot be removed from the cluster by mistakenly omitting it from the updated value of option osd-devices.


To keep the documentation consistent, I suggest changing the juju ssh ceph-mon/1 sudo ceph status command to juju ssh ceph-mon/leader sudo ceph status here as well.

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Done, thanks.

(make 20 characters so Discourse is happy)

I believe that “On any MON (unit ceph-mon/1 is just an example) run a status check” would also need to be rephrased. (Same sentence also in Adding MONs).

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