Decommissioning or permanently removing a tablet server from a cluster

Starting with Kudu 1.12, the Kudu rebalancer tool can be used to decommission a tablet server by supplying the --ignored_tservers and --move_replicas_from_ignored_tservers arguments.

Ensure the cluster is in good health using ksck.
Put the tablet server into a maintenance mode by using the kudu tserver state enter_maintenance tool.
Run the kudu cluster rebalance tool, supplying the --ignored_tservers argument with the UUIDs of the tablet servers to be decommissioned, and the --move_replicas_from_ignored_tservers flag.
Wait for the moves to complete and for ksck to show the cluster in a healthy state.
The decommissioned tablet server can be brought offline.
To completely remove it from the cluster so ksck shows the cluster as completely healthy, restart the masters.
If you have only one master in your deployment, this may cause cluster downtime. In a multi-master deployment, restart the masters in sequence to avoid cluster downtime.