We will now learn what these flags are and why they are used:

• noout: This forces the Ceph cluster to not mark any OSD as out of the cluster, irrespective of its status. It makes sure all the OSDs remain inside the cluster.
• nodown: This forces the Ceph cluster to not mark any OSD down, irrespective of its status. It makes sure all the OSDs remain UP and none of them DOWN.
• noup: This forces the Ceph cluster to not mark any down OSD as UP. So, any OSD that is marked DOWN can only come UP after this flag is unset. This also applies to new OSDs that are joining the cluster.
• noin: This forces the Ceph cluster to not allow any new OSD to join the cluster. This is quite useful if you are adding several OSDs at once and don't want them to join the cluster automatically.
• norecover: This forces the Ceph cluster to not perform cluster recovery.
• nobackfill: This forces the Ceph cluster to not perform backfilling. This is quite useful when you are adding several OSDs at once and don't want Ceph to perform automatic data placement on the new node.
• norebalance: This forces the Ceph cluster to not perform cluster rebalancing.
• noscrub: This forces Ceph to not perform OSD scrubbing.
• nodeep-scrub: This forces Ceph to not perform OSD deep scrubbing.