[Gluster-users] Rebalancing newly added bricks

[Herb Burnswell]

All,

RHEL 7.5
Gluster 3.8.15
2 Nodes: serverA & serverB

I am not deeply knowledgeable about Gluster and it's administration but we
have a 2 node cluster that's been running for about a year and a half.  All
has worked fine to date.  Our main volume has consisted of two 60TB bricks
on each of the cluster nodes.  As we reached capacity on the volume we
needed to expand.  So, we've added four new 60TB bricks to each of the
cluster nodes.  The bricks are now seen, and the total size of the volume
is as expected:

# gluster vol status tank
Status of volume: tank
Gluster process                             TCP Port  RDMA Port  Online  Pid
------------------------------------------------------------------------------
Brick serverA:/gluster_bricks/data1       49162     0          Y       20318
Brick serverB:/gluster_bricks/data1       49166     0          Y       3432
Brick serverA:/gluster_bricks/data2       49163     0          Y       20323
Brick serverB:/gluster_bricks/data2       49167     0          Y       3435
Brick serverA:/gluster_bricks/data3       49164     0          Y       4625
Brick serverA:/gluster_bricks/data4       49165     0          Y       4644
Brick serverA:/gluster_bricks/data5       49166     0          Y       5088
Brick serverA:/gluster_bricks/data6       49167     0          Y       5128
Brick serverB:/gluster_bricks/data3       49168     0          Y       22314
Brick serverB:/gluster_bricks/data4       49169     0          Y       22345
Brick serverB:/gluster_bricks/data5       49170     0          Y       22889
Brick serverB:/gluster_bricks/data6       49171     0          Y       22932
Self-heal Daemon on localhost             N/A       N/A        Y       22981
Self-heal Daemon on serverA.example.com   N/A       N/A        Y       6202

After adding the bricks we ran a rebalance from serverA as:

# gluster volume rebalance tank start

The rebalance completed:

# gluster volume rebalance tank status
                                    Node Rebalanced-files          size
  scanned      failures       skipped               status  run time in
h:m:s
                               ---------      -----------   -----------
-----------   -----------   -----------         ------------
--------------
                               localhost                0        0Bytes
        0             0             0            completed        3:7:10
                             serverA.example.com        0        0Bytes
        0             0             0            completed        0:0:0
volume rebalance: tank: success

However, when I run a df, the two original bricks still show all of the
consumed space (this is the same on both nodes):

# df -hP
Filesystem                               Size  Used Avail Use% Mounted on
/dev/mapper/vg0-root                     5.0G  625M  4.4G  13% /
devtmpfs                                  32G     0   32G   0% /dev
tmpfs                                     32G     0   32G   0% /dev/shm
tmpfs                                     32G   67M   32G   1% /run
tmpfs                                     32G     0   32G   0%
/sys/fs/cgroup
/dev/mapper/vg0-usr                       20G  3.6G   17G  18% /usr
/dev/md126                              1014M  228M  787M  23% /boot
/dev/mapper/vg0-home                     5.0G   37M  5.0G   1% /home
/dev/mapper/vg0-opt                      5.0G   37M  5.0G   1% /opt
/dev/mapper/vg0-tmp                      5.0G   33M  5.0G   1% /tmp
/dev/mapper/vg0-var                       20G  2.6G   18G  13% /var
/dev/mapper/gluster_vg-gluster_lv1_data   60T   59T  1.1T  99%
/gluster_bricks/data1
/dev/mapper/gluster_vg-gluster_lv2_data   60T   58T  1.3T  98%
/gluster_bricks/data2
/dev/mapper/gluster_vg-gluster_lv3_data   60T  451M   60T   1%
/gluster_bricks/data3
/dev/mapper/gluster_vg-gluster_lv4_data   60T  451M   60T   1%
/gluster_bricks/data4
/dev/mapper/gluster_vg-gluster_lv5_data   60T  451M   60T   1%
/gluster_bricks/data5
/dev/mapper/gluster_vg-gluster_lv6_data   60T  451M   60T   1%
/gluster_bricks/data6
localhost:/tank                          355T  116T  239T  33% /mnt/tank

We were thinking that the used space would be distributed across the now 6
bricks after rebalance.  Is that not what a rebalance does?  Is this
expected behavior?

Can anyone provide some guidance as to what the behavior here and if there
is anything that we need to do at this point?

Thanks in advance,

HB
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