nodetool decommission¶

decommission - Deactivate a selected node by streaming its data to the next node in the ring.

For example:

nodetool decommission

Use the nodetool netstats command to monitor the progress of the token reallocation.

See Remove a Node from a ScyllaDB Cluster (Down Scale) for procedure details.

Before you run nodetool decommission:

• Review current disk space utilization on existing nodes and make sure the amount of data streamed from the node being removed can fit into the disk space available on the remaining nodes. If there is not enough disk space on the remaining nodes, the removal of a node will fail. Add more storage to remaining nodes before starting the removal procedure.

• Make sure that the number of nodes remaining in the DC after you decommission a node will be the same or higher than the Replication Factor configured for the keyspace in this DC. If the number of remaining nodes is lower than the RF, the decommission request may fail. In such a case, ALTER the keyspace to reduce the RF before running nodetool decommission.

It’s allowed to invoke nodetool decommission on multiple nodes in parallel. This will be faster than doing it sequentially if there is significant amount of data in tablet-based keyspaces, because tablets are migrated from nodes in parallel. Decommission process first migrates tablets away, and this part is done in parallel for all nodes being decommissioned. Then it does the vnode-based decommission, and this part is serialized with other vnode-based operations, including those from other decommission operations.

Decommission which is still in the tablet draining phase can be canceled using Task Manager API. See Task manager.

Nodetool Reference