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8.3. Expanding Volumes

Volumes can be expanded while the trusted storage pool is online and available. For example, you can add a brick to a distributed volume, which increases distribution and adds capacity to the Red Hat Storage volume. Similarly, you can add a group of bricks to a distributed replicated volume, which increases the capacity of the Red Hat Storage volume.

Note

When expanding distributed replicated or distributed striped volumes, the number of bricks being added must be a multiple of the replica or stripe count. For example, to expand a distributed replicated volume with a replica count of 2, you need to add bricks in multiples of 2 (such as 4, 6, 8, etc.).

Expanding a Volume

  1. From any server in the trusted storage pool, use the following command to probe the server on which you want to add a new brick : 
    # gluster peer probe HOSTNAME
    For example: 
    # gluster peer probe server4
Probe successful
  2. Add the brick using the following command: 
    # gluster volume add-brick VOLNAME NEW_BRICK
    For example: 
    # gluster volume add-brick test-volume server4:/exp4
Add Brick successful
    If you want to change the replica/stripe count, you must add the replica/stripe count to the add-brick command.
    For example, 
    # gluster volume add-brick replica 2 test-volume server4:/exp4
    When increasing the replica/stripe count of a distribute replicate/stripe volume, the number of replica/stripe bricks to be added must be equal to the number of distribute subvolumes.
  3. Check the volume information using the following command: 
    # gluster volume info
    The command output displays information similar to the following: 
    Volume Name: test-volume
Type: Distribute-Replicate
Status: Started
Number of Bricks: 4
Bricks:
Brick1: server1:/exp1
Brick2: server2:/exp2
Brick3: server3:/exp3
Brick4: server4:/exp4
  4. Rebalance the volume to ensure that files are distributed to the new brick. Use the rebalance command as described in Section 8.7, “Rebalancing Volumes”.

Important

The add-brick command should be followed by a rebalance operation to ensure better utilization of the added bricks.