[Gluster-users] Rebalancing in 3.1 not working

Dan Bretherton d.a.bretherton at reading.ac.uk
Sun Nov 21 11:57:25 UTC 2010

Hello all-
I have just added two replicated bricks (2x2) to a
distributed-replicated volume.  When mounted the new size is correct
(11TB) and the "gluster volume info" shows what I would expect.  However
rebalancing the volume seems to have no effect, and happens almost
instantaneously.  I expected it to take several hours because the
original bricks have 5TB on them.  These are the commands I ran to start
the rebalance and check the status.

[root at bdan4 ~]# gluster volume rebalance atmos start
starting rebalance on volume atmos has been successful
[root at bdan4 ~]# gluster volume rebalance atmos status
rebalance completed

These are the last two messages in etc-glusterfs-glusterd.vol.log

[2010-11-21 11:34:52.316470] I
[glusterd-rebalance.c:292:glusterd_defrag_start] rebalance: rebalance on
/etc/glusterd/mount/atmos complete
[2010-11-21 11:35:04.653629] I
[glusterd-rebalance.c:385:glusterd_handle_defrag_volume] glusterd:
Received rebalance volume on atmos

The messages look to me as if they are in the wrong order.  I confirmed
this with another "gluster volume rebalance atmos status", which results
in the message "Received rebalance volume on atmos".

It wondered if it would have been better to add just one replicated
brick at a time instead of two at once, but when I went to remove one of
them I was scared off by the warning about possible data loss.  The new
volume does seem to be working and some files are being put on the new
bricks, but most seem to be going onto the original bricks which were
~80% full before the expansion.  I would like to press on and use the
volume but I don't know what will happen when the original bricks get
completely full, and there is also likely to be a performance penalty in
using an un-balanced volume, as I understand it from reading previous
mailing list postings.  Any suggestions would be much appreciated.


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