The software described in this documentation is either no longer supported or is in extended support.
Oracle recommends that you upgrade to a current supported release.

3.4.6 Shrinking a Volume

You can decrease the number of bricks in a volume. This may be useful if a node in the Gluster pool encounters a hardware or network fault.

When shrinking distributed replicated and distributed dispersed volumes, you need to remove a number of bricks that is a multiple of the replica or stripe count. For example, to shrink a distributed replicate volume with a replica count of 2, you need to remove bricks in multiples of 2 (such as 4, 6, 8, and so on). The bricks you remove must be from the same replica or disperse set.

To shrink a volume:

  1. Remove the brick(s), for example: 

    # gluster volume remove-brick myvolume node4:/data/glusterfs/myvolume/mybrick/brick start

    The start option automatically triggers a volume rebalance operation to migrate data from the removed brick(s) to other bricks in the volume.

  2. You can check the status of the brick removal using: 

    # gluster volume remove-brick myvolume status

  3. When the brick-removal status is completed, commit the remove-brick operation. For example: 

    # gluster volume remove-brick myvolume commit

    You are requested to confirm the operation. Enter y to confirm that you want to delete the brick(s).

    The data on the brick is migrated to other bricks in the pool. The data on the removed brick is no longer accessible at the Gluster mount point. Removing the brick removes the configuration information and not the data. You can continue to access the data directly from the brick if required.

Example 3.13 Removing a node from a distributed replicated volume

This example removes a node from a pool with four nodes. The replica count for this volume is 4. As a node is removed, the replica count must be reduced to 3. The start option is not needed in replicated volumes, instead, you should use the force option. The force option means you do not need to check the remove-brick process status, or perform the remove-brick commit steps. 

# gluster volume info
 
Volume Name: myvolume
Type: Distributed-Replicate
Volume ID: ...
Status: Started
Snapshot Count: 0
Number of Bricks: 4 x 4 = 16
Transport-type: tcp
Bricks:
Brick1: node1:/data/glusterfs/myvolume/mybrick/brick1
Brick2: node2:/data/glusterfs/myvolume/mybrick/brick1
Brick3: node3:/data/glusterfs/myvolume/mybrick/brick1
Brick4: node4:/data/glusterfs/myvolume/mybrick/brick1
Brick5: node1:/data/glusterfs/myvolume/mybrick/brick2
Brick6: node2:/data/glusterfs/myvolume/mybrick/brick2
Brick7: node3:/data/glusterfs/myvolume/mybrick/brick2
Brick8: node4:/data/glusterfs/myvolume/mybrick/brick2
Brick9: node1:/data/glusterfs/myvolume/mybrick/brick3
Brick10: node2:/data/glusterfs/myvolume/mybrick/brick3
Brick11: node3:/data/glusterfs/myvolume/mybrick/brick3
Brick12: node4:/data/glusterfs/myvolume/mybrick/brick3
Brick13: node1:/data/glusterfs/myvolume/mybrick/brick4
Brick14: node2:/data/glusterfs/myvolume/mybrick/brick4
Brick15: node3:/data/glusterfs/myvolume/mybrick/brick4
Brick16: node4:/data/glusterfs/myvolume/mybrick/brick4
Options Reconfigured:
transport.address-family: inet
nfs.disable: on
performance.client-io-threads: off
# gluster volume remove-brick myvolume replica 3 \
  node4:/data/glusterfs/myvolume/mybrick/brick1 \
  node4:/data/glusterfs/myvolume/mybrick/brick2 \
  node4:/data/glusterfs/myvolume/mybrick/brick3 \
  node4:/data/glusterfs/myvolume/mybrick/brick4 \
  force 
# gluster volume info
 
Volume Name: myvolume
Type: Distributed-Replicate
Volume ID: ...
Status: Started
Snapshot Count: 0
Number of Bricks: 4 x 3 = 12
Transport-type: tcp
Bricks:
Brick1: node1:/data/glusterfs/myvolume/mybrick/brick1
Brick2: node2:/data/glusterfs/myvolume/mybrick/brick1
Brick3: node3:/data/glusterfs/myvolume/mybrick/brick1
Brick4: node1:/data/glusterfs/myvolume/mybrick/brick2
Brick5: node2:/data/glusterfs/myvolume/mybrick/brick2
Brick6: node3:/data/glusterfs/myvolume/mybrick/brick2
Brick7: node1:/data/glusterfs/myvolume/mybrick/brick3
Brick8: node2:/data/glusterfs/myvolume/mybrick/brick3
Brick9: node3:/data/glusterfs/myvolume/mybrick/brick3
Brick10: node1:/data/glusterfs/myvolume/mybrick/brick4
Brick11: node2:/data/glusterfs/myvolume/mybrick/brick4
Brick12: node3:/data/glusterfs/myvolume/mybrick/brick4
Options Reconfigured:
transport.address-family: inet
nfs.disable: on
performance.client-io-threads: off
# gluster peer detach node4
peer detach: success
# gluster peer status
Number of Peers: 2

Hostname: node2
Uuid: ...
State: Peer in Cluster (Connected)

Hostname: node3
Uuid: ...
State: Peer in Cluster (Connected)

Example 3.14 Removing bricks from a distributed replicated volume

This example removes two bricks from a distributed replicated volume. 

# gluster volume info
 
Volume Name: myvolume
Type: Distributed-Replicate
Volume ID: ...
Status: Started
Snapshot Count: 0
Number of Bricks: 4 x 3 = 12
Transport-type: tcp
Bricks:
Brick1: node1:/data/glusterfs/myvolume/mybrick/brick1
Brick2: node2:/data/glusterfs/myvolume/mybrick/brick1
Brick3: node3:/data/glusterfs/myvolume/mybrick/brick1
Brick4: node1:/data/glusterfs/myvolume/mybrick/brick2
Brick5: node2:/data/glusterfs/myvolume/mybrick/brick2
Brick6: node3:/data/glusterfs/myvolume/mybrick/brick2
Brick7: node1:/data/glusterfs/myvolume/mybrick/brick3
Brick8: node2:/data/glusterfs/myvolume/mybrick/brick3
Brick9: node3:/data/glusterfs/myvolume/mybrick/brick3
Brick10: node1:/data/glusterfs/myvolume/mybrick/brick4
Brick11: node2:/data/glusterfs/myvolume/mybrick/brick4
Brick12: node3:/data/glusterfs/myvolume/mybrick/brick4
Options Reconfigured:
transport.address-family: inet
nfs.disable: on
performance.client-io-threads: off
# gluster volume remove-brick myvolume \
  node{1,2,3}:/data/glusterfs/myvolume/mybrick/brick3 \
  node{1,2,3}:/data/glusterfs/myvolume/mybrick/brick4 \
  start
volume remove-brick start: success
ID: ...
# gluster volume remove-brick myvolume \
  node{1,2,3}:/data/glusterfs/myvolume/mybrick/brick3 \
  node{1,2,3}:/data/glusterfs/myvolume/mybrick/brick4 \
  status
     Node ...        status  run time in h:m:s
--------- ...  ------------     --------------
localhost ...  completed        0:00:00
node2     ...  completed        0:00:00
node3     ...  completed        0:00:01

# gluster volume remove-brick myvolume \
  node{1,2,3}:/data/glusterfs/myvolume/mybrick/brick3 \
  node{1,2,3}:/data/glusterfs/myvolume/mybrick/brick4 \
  commit
Removing brick(s) can result in data loss. Do you want to Continue? (y/n) y
volume remove-brick commit: success
Check the removed bricks to ensure all files are migrated.
If files with data are found on the brick path, copy them via a gluster mount 
point before re-purposing the removed brick. 
# gluster volume info
 
Volume Name: myvolume
Type: Distributed-Replicate
Volume ID: ...
Status: Started
Snapshot Count: 0
Number of Bricks: 2 x 3 = 6
Transport-type: tcp
Bricks:
Brick1: node1:/data/glusterfs/myvolume/mybrick/brick1
Brick2: node2:/data/glusterfs/myvolume/mybrick/brick1
Brick3: node3:/data/glusterfs/myvolume/mybrick/brick1
Brick4: node1:/data/glusterfs/myvolume/mybrick/brick2
Brick5: node2:/data/glusterfs/myvolume/mybrick/brick2
Brick6: node3:/data/glusterfs/myvolume/mybrick/brick2
Options Reconfigured:
transport.address-family: inet
nfs.disable: on
performance.client-io-threads: off

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