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Hi Ravi,
Thanks for the clarification. For one reason or another I thought there was no longer a way to shrink a gluster filesystem but it appears from testing you are correct. I generated 100 test files on a 2node/4 ebs brick distributed gluster volume, removed one
brick, committed and ended up having those files successfully migrated to the remaining 3 bricks.
Volume Name: volume1
Type: Distribute
Volume ID: 1180f5ec-af82-4322-8fc2-1add01161442
Status: Started
Number of Bricks: 4
Transport-type: tcp
Bricks:
Brick1: gluster1.local:/export/xvdf/brick
Brick2: gluster1.local:/export/xvdg/brick
Brick3: gluster2.local:/export/xvdf/brick
Brick4: gluster2.local:/export/xvdg/brick
[root@ip-172-31-19-77 ~]#
Gluster1
[root@ip-172-31-19-77 ~]# ls /export/xvdf/brick/
1 13 24 26 33 47 48 5 51 53 54 58 61 62 64 65 70 72 73 8 9 91 94 96 97 98
[root@ip-172-31-19-77 ~]# ls /export/xvdg/brick/
11 18 19 20 23 27 28 32 35 38 44 46 49 63 68 69 7 78 79 82 85 86 88 93 99
[root@ip-172-31-19-77 ~]# ls /export/xvdf/brick/ | wc -l
26
[root@ip-172-31-19-77 ~]# ls /export/xvdg/brick/ | wc -l
25
Gluster2
[ec2-user@ip-172-31-19-78 ~]$ ls /export/xvdf/brick/
16 22 29 30 34 37 4 41 43 56 57 60 71 74 75 76 80 83 89 90 92
[ec2-user@ip-172-31-19-78 ~]$ ls /export/xvdg/brick/
10 12 15 2 25 31 39 42 50 55 6 67 81 87
100 14 17 21 3 36 40 45 52 59 66 77 84 95
[ec2-user@ip-172-31-19-78 ~]$ ls /export/xvdg/brick/ | wc -l
28
[ec2-user@ip-172-31-19-78 ~]$ ls /export/xvdf/brick/ | wc -l
21
Remove Brick Operation
[root@ip-172-31-19-77 ~]# gluster volume remove-brick volume1 gluster1.local:/export/xvdf/brick start
volume remove-brick start: success
ID: b0a6decd-9130-4773-97f9-af108ff0bd77
[root@ip-172-31-19-77 ~]# gluster volume remove-brick volume1 gluster1.local:/export/xvdf/brick status
Node Rebalanced-files size scanned failures skipped status run time in secs
--------- ----------- ----------- ----------- ----------- ----------- ------------ --------------
localhost 41 0Bytes 141 0 0 completed 1.00
[root@ip-172-31-19-77 ~]# gluster volume remove-brick volume1 gluster1.local:/export/xvdf/brick commit
Removing brick(s) can result in data loss. Do you want to Continue? (y/n) y
volume remove-brick commit: success
[root@ip-172-31-19-77 ~]# gluster volume info volume1
Volume Name: volume1
Type: Distribute
Volume ID: 1180f5ec-af82-4322-8fc2-1add01161442
Status: Started
Number of Bricks: 3
Transport-type: tcp
Bricks:
Brick1: gluster1.local:/export/xvdg/brick
Brick2: gluster2.local:/export/xvdf/brick
Brick3: gluster2.local:/export/xvdg/brick
I checked the brick mount points and the overall gluster mount point and found that it did indeed migrate the data from the removed brick to the others and all files were accounted for.
I checked the most recent documentation on github here https://github.com/gluster/glusterfs/blob/master/doc/admin-guide/en-US/markdown/admin_managing_volumes.md#shrinking-volumes and
found only examples for 'remove-brick force' (which obviously doesn't migrate any data) and 'replace-brick' (which is now deprecated but isn't noted as such in the docs). I'm left wondering why they don't have a non-forceful remove-brick operation documented
for people that simply want to remove a brick while migrating data to remaining bricks.
Am I missing something or this common use case undocumented?
John
From: Ravishankar N
Date: Wednesday, April 1, 2015 at 9:38 AM To: John Lilley, "gluster-users@xxxxxxxxxxx" Subject: Re: [Gluster-users] Shrinking gluster filesystem in 3.6.2 On 03/31/2015 05:12 AM, Lilley, John F. wrote:
If I understand you correctly, you want to replace a brick in a distribute volume with one of lesser capacity. You could first add a new brick and then remove the existing brick with remove-brick start/status/commit sequence. Something like this: ------------------------------------------------ [root@tuxpad ~]# gluster volume info testvol Volume Name: testvol Type: Distribute Volume ID: a89aa154-885c-4e14-8d3a-b555733b11f1 Status: Started Number of Bricks: 3 Transport-type: tcp Bricks: Brick1: 127.0.0.2:/home/ravi/bricks/brick1 Brick2: 127.0.0.2:/home/ravi/bricks/brick2 Brick3: 127.0.0.2:/home/ravi/bricks/brick3 [root@tuxpad ~]# [root@tuxpad ~]# [root@tuxpad ~]# gluster volume add-brick testvol 127.0.0.2:/home/ravi/bricks/brick{4..6} volume add-brick: success [root@tuxpad ~]# [root@tuxpad ~]# gluster volume info testvol Volume Name: testvol Type: Distribute Volume ID: a89aa154-885c-4e14-8d3a-b555733b11f1 Status: Started Number of Bricks: 6 Transport-type: tcp Bricks: Brick1: 127.0.0.2:/home/ravi/bricks/brick1 Brick2: 127.0.0.2:/home/ravi/bricks/brick2 Brick3: 127.0.0.2:/home/ravi/bricks/brick3 Brick4: 127.0.0.2:/home/ravi/bricks/brick4 Brick5: 127.0.0.2:/home/ravi/bricks/brick5 Brick6: 127.0.0.2:/home/ravi/bricks/brick6 [root@tuxpad ~]# [root@tuxpad ~]# [root@tuxpad ~]# [root@tuxpad ~]# gluster v remove-brick testvol 127.0.0.2:/home/ravi/bricks/brick{1..3} start volume remove-brick start: success ID: d535675e-8362-4a44-a291-1e567a77531e [root@tuxpad ~]# gluster v remove-brick testvol 127.0.0.2:/home/ravi/bricks/brick{1..3} status Node Rebalanced-files size scanned failures skipped status run time in secs --------- ----------- ----------- ----------- ----------- ----------- ------------ -------------- localhost 10 0Bytes 20 0 0 completed 0.00 [root@tuxpad ~]# [root@tuxpad ~]# gluster v remove-brick testvol 127.0.0.2:/home/ravi/bricks/brick{1..3} 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. [root@tuxpad ~]# [root@tuxpad ~]# gluster volume info testvol Volume Name: testvol Type: Distribute Volume ID: a89aa154-885c-4e14-8d3a-b555733b11f1 Status: Started Number of Bricks: 3 Transport-type: tcp Bricks: Brick1: 127.0.0.2:/home/ravi/bricks/brick4 Brick2: 127.0.0.2:/home/ravi/bricks/brick5 Brick3: 127.0.0.2:/home/ravi/bricks/brick6 [root@tuxpad ~]# ------------------------------------------------ Hope this helps. Ravi
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