That message uses add + remove. You did remove + add. Maybe that matters? Sent from my iPad > On 11 Apr 2014, at 23:38, Andrew Smith <smith.andrew.james@xxxxxxxxx> wrote: > > > My understanding is that “replace-brick” is deprecated > > http://www.gluster.org/pipermail/gluster-users/2012-October/034473.html > > And that the “add-brick” followed by “remove-brick” should behave > the same way. > > It does not behave as predicted, I think, because my system is > unbalanced. I have no idea whether or no the “replace-brick” > command will behave differently. > > Andy > > >> On Apr 11, 2014, at 5:34 PM, Machiel Groeneveld <machielg@xxxxxxxxx> wrote: >> >> Isn't that what replace-brick is for? >> >> >>> On 11 Apr 2014, at 23:32, Andrew Smith <smith.andrew.james@xxxxxxxxx> wrote: >>> >>> >>> Hi, I have a problem, which I hope for your sake, is uncommon. >>> >>> I built a Gluster volume with 8 bricks, 4 80TB and 4 68TB with >>> a total capacity of about 600TB. The underlying filesystem >>> is BTRFS. >>> >>> I found out after the system was half full that BTRFS was a >>> bad idea. BTRFS doesn’t have inodes. It allocates some fraction >>> of the disk space to metadata and when it runs out, it allocates >>> more. This allocation process on large volumes is painfully slow >>> and brings effective write speeds down to only a few MB/s with long >>> timeouts. The data can be read at high speeds, but writing to the >>> volume is a big fat mess. Reading is still fairly fast though, >>> so access to the my data by users is acceptable. >>> >>> I need to keep this volume available and I don’t have a second >>> copy of the hardware to rebuild the system on. So, I need to do >>> an in-situ transition from BTRFS to XFS. >>> >>> To do this, I first cleared out some data to free up metadata space, >>> and then with much difficulty managed to do a >>> >>> # gluster volume remove-brick >>> >>> I retired the removed brick and then reformatted it with XFS and added >>> it back to my Gluster volume. At this point, I thought I was nearly >>> home. I thought I could retire a second brick and the data would >>> be copied to the empty brick. However, this is not what happens. >>> Some data ends up on the newly added brick, but some of the data >>> flows elsewhere, which due to the BTRFS problem is a nightmare. >>> >>> I assume this is because when I took my volume from 8 bricks to 7, it >>> became unbalanced. The data on the brick that I was retiring >>> belongs on several different bricks and so I am not just doing a >>> substitution. >>> >>> I need to be able to tell my Gluster volume to include all the bricks, >>> but do not write files to any of the BTRFS bricks so that it puts data >>> only on the XFS brick. If I could somehow tell Gluster that these bricks >>> were full, that would suffice. >>> >>> I could do a "rebalance migrate-data" to make make the data on the BTRFS >>> volumes more uniform, but I don’t know how this will work. Does reposition >>> the data brick by brick or file by file. Brick by brick would be bad, since >>> the last brick to rebalance would need to receive all the data that it requires >>> before it would get to write data out to free up metadata space. >>> >>> There is a “rebalance-brick” option in the man page, but I don’t see that >>> documented. This may be useful, but I have no idea what it will do. >>> >>> Is there a solution to my problem? Whip it and start over is not helpful. >>> Any help on how I can predict where data will go will also help. >>> >>> Andy >>> _______________________________________________ >>> Gluster-users mailing list >>> Gluster-users@xxxxxxxxxxx >>> http://supercolony.gluster.org/mailman/listinfo/gluster-users > _______________________________________________ Gluster-users mailing list Gluster-users@xxxxxxxxxxx http://supercolony.gluster.org/mailman/listinfo/gluster-users
