Override use cases

Understand various overrride use cases.

• noin: Commonly used with noout to address flapping OSDs.

• noout: If the mon osd report timeout is exceeded and an OSD has not reported to the monitor, the OSD will get marked out. If this happens erroneously, you can set noout to prevent the OSD(s) from getting marked out while you troubleshoot the issue.

• noup: Commonly used with nodown to address flapping OSDs.

• nodown: Networking issues may interrupt Ceph heartbeat processes, and an OSD may be up but still get marked down. You can set nodown to prevent OSDs from getting marked down while troubleshooting the issue.

• full: If a cluster is reaching its full_ratio, you can pre-emptively set the cluster to full and expand capacity.

  Note: Setting the cluster to full will prevent write operations.

• pause: If you need to troubleshoot a running Ceph cluster without clients reading and writing data, you can set the cluster to pause to prevent client operations.

• nobackfill: If you need to take an OSD or node down temporarily, for example, upgrading daemons, you can set nobackfill so that Ceph will not backfill while the OSDs is down.

• norecover: If you need to replace an OSD disk and don’t want the PGs to recover to another OSD while you are hotswapping disks, you can set norecover to prevent the other OSDs from copying a new set of PGs to other OSDs.

• noscrub and nodeep-scrubb: If you want to prevent scrubbing for example, to reduce overhead during high loads, recovery, backfilling, and rebalancing you can set noscrub and/or nodeep-scrub to prevent the cluster from scrubbing OSDs.

• notieragent: If you want to stop the tier agent process from finding cold objects to flush to the backing storage tier, you may set notieragent.