Migrating a Volume off a Node Using the CLI

When you need to migrate a data volume off a particular node, move that node from the /data path to the /decommissioned path to avoid data under-replication.

  • Establish a /data topology path to serve as the default topology path for the volumes in that cluster.
  • Establish a /decommissioned topology path that is not assigned to any volumes.
TIP
It is recommended that CLDB and ZooKeeper nodes are not in the same topology as the data nodes to ensure fast failover of the failed data node in the event of a data node failure.

Since no data volumes are assigned to the /decommissioned topology path , standard data replication will migrate the data off that node to other nodes that are still in the /data topology path.

You can run the following command to check if a given volume is present on a specified node:

maprcli dump volumenodes -volumename <volume> -json | grep <ip:port>

Run this command for each non-local volume in your cluster. Once all the data has migrated off the node, you can decommission the node or place it in maintenance mode.

If you need to segregate CLDB data, create a /cldb topology node and move the CLDB nodes under /cldb. Point the topology for the CLDB volume (mapr.cldb.internal) to /cldb. See Isolating CLDB Nodes for details.

NOTE
To move an existing volume to another topology, you must have the Converged Enterprise Edition. Without the Converged Enterprise Edition, when you run the maprcli volume move command to move a volume to another topology, the following error message is returned: 
ERROR (10010) - Volume Move: No license for requested operation