Storage Container Manager Leader Transfer

The ozone admin scm transfer command allows you to manually transfer the leadership of the Storage Container Manager (SCM) Raft group to a specific SCM node or to a randomly chosen follower.

Be aware of the node's status(eg. Safemode, Operational status), Ozone currently has no ability to check the target node's status before transferring the leadership.

Until HDDS-17124 is fixed, manual OM and SCM leadership transfer commands have taken approximately 4–13 seconds in five-node tests because of Ratis client retry waits during leader discovery and priority reset. This is an observation, not an upper bound or a guarantee about automatic failover latency. Account for client RPC timeouts; if a command times out, check the current roles before deciding whether to retry.

Usage

ozone admin scm transfer -id <SCM_SERVICE_ID> -n <NEW_LEADER_ID>
ozone admin scm transfer -id <SCM_SERVICE_ID> -r

• -id, --service-id: Specifies the SCM Service ID.
• -n, --newLeaderId, --new-leader-id: The SCM UUID (Raft peer ID) of the SCM to which leadership will be transferred (e.g., e6877ce5-56cd-4f0b-ad60-4c8ef9000882).
• -r, --random: Randomly chooses a follower to transfer leadership to.

Example

To transfer leadership to a specific SCM in a cluster with service ID cluster1:

ozone admin scm transfer -id cluster1 -n e6877ce5-56cd-4f0b-ad60-4c8ef9000882

To transfer leadership to a random follower:

ozone admin scm transfer -id cluster1 -r