10.5. Rebalancing Volumes

After expanding or shrinking (without migrating data) a volume (using the add-brick and remove-brick commands respectively), you need to rebalance the data among the servers. In a non-replicated volume, all bricks should be up to perform replace brick operation (start option). In a replicated volume, at least one of the brick in the replica should be up.

Important

In Red Hat Storage 2.0 Update 4 release, the fix-layout step after adding a brick has been deprecated. When a brick is added, the distributed hash table is modified automatically.

To rebalance a volume

Start the rebalance operation on any one of the servers using the following command:
# gluster volume rebalance VOLNAME start
For example:
```
# gluster volume rebalance test-volume start
Starting rebalancing on volume test-volume has been successful
```
Start the migration operation forcefully on any one of the servers using the following command:
# gluster volume rebalance VOLNAME start force
For example:
```
# gluster volume rebalance test-volume start force
Starting rebalancing on volume test-volume has been successful
```

10.5.1. Displaying Status of Rebalance Operation

You can display the status information about rebalance volume operation, as needed.

To view status of rebalance volume

Check the status of the rebalance operation, using the following command:

# gluster volume rebalance VOLNAME status

For example:

# gluster volume rebalance test-volume status
     Node    Rebalanced-files          size       scanned      failures         status
---------         -----------   -----------   -----------   -----------   ------------
localhost                 112         14567           150            0    in progress
10.16.156.72              140          2134           201            2    in progress

The time to complete the rebalance operation depends on the number of files on the volume along with the corresponding file sizes. Continue checking the rebalance status, verifying that the number of files rebalanced or total files scanned keeps increasing.

For example, running the status command again might display a result similar to the following:

# gluster volume rebalance test-volume status
     Node    Rebalanced-files          size       scanned      failures         status
---------         -----------   -----------   -----------   -----------   ------------
localhost                 112         14567           150            0    in progress
10.16.156.72              140          2134           201            2    in progress

The rebalance status displays the following when the rebalance is complete:

# gluster volume rebalance test-volume status
     Node    Rebalanced-files          size       scanned      failures         status
---------         -----------   -----------   -----------   -----------   ------------
localhost                 112         15674           170            0       completed
10.16.156.72              140          3423           321            2       completed