[Gluster-users] Strange behaviour with add-brick followed by remove-brick

[Lalatendu Mohanty]

On 10/30/2013 09:10 PM, Brian Cipriano wrote:
> I had the exact same experience recently with a 3.4 distributed 
> cluster I set up. I spent some time on the IRC but couldn’t track it 
> down. Seems remove-brick is broken in 3.3 and 3.4. I guess folks don’t 
> remove bricks very often :)
>
> - brian
>

Brian,

I have tried remove brick couple of times and it worked for me. From 
your experiance  it seems remove brick has a bug. I will suggest you to 
file a bug  or give us steps to reproduce , so that I can reproduce it 
in my environment and file a bug for it.

>
>
>
> On Oct 30, 2013, at 11:21 AM, Lalatendu Mohanty <lmohanty at redhat.com 
> <mailto:lmohanty at redhat.com>> wrote:
>
>> On 10/30/2013 08:40 PM, Lalatendu Mohanty wrote:
>>> On 10/30/2013 03:43 PM, B.K.Raghuram wrote:
>>>> I have gluster 3.4.1 on 4 boxes with hostnames n9, n10, n11, n12. I
>>>> did the following sequence of steps and ended up with losing data so
>>>> what did I do wrong?!
>>>>
>>>> - Create a distributed volume with bricks on n9 and n10
>>>> - Started the volume
>>>> - NFS mounted the volume and created 100 files on it. Found that n9
>>>> had 45, n10 had 55
>>>> - Added a brick n11 to this volume
>>>> - Removed a brick n10 from the volume with gluster remove brick <vol>
>>>> <n10 brick name> start
>>>> - n9 now has 45 files, n10 has 55 files and n11 has 45 files(all the
>>>> same as on n9)
>>>> - Checked status, it shows that no rebalanced files but that n10 had
>>>> scanned 100 files and completed. 0 scanned for all the others
>>>> - I then did a rebalance start force on the vol and found that n9 had
>>>> 0 files, n10 had 55 files and n11 had 45 files - weird - looked like
>>>> n9 had been removed but double checked again and found that n10 had
>>>> indeed been removed.
>>>> - did a remove-brick commit. Now same file distribution after that.
>>>> volume info now shows the volume to have n9 and n11 and bricks.
>>>> - did a rebalance start again on the volume. The rebalance-status now
>>>> shows n11 had 45 rebalanced files, all the brick nodes had 45 files
>>>> scanned and all show complete. The file layout after this is n9 has 45
>>>> files and n10 has 55 files. n11 has 0 files!
>>>> - An ls on the nfs mount now shows only 45 files so the other 55 not
>>>> visible because they are on n10 which is not part of the volume!
>>>>
>>>> What have I done wrong in this sequence?
>>>> _______________________________________________
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>>>> Gluster-users at gluster.org
>>>> http://supercolony.gluster.org/mailman/listinfo/gluster-users
>>> |
>>> I think running rebalnce (force) in between "remove brick start" and 
>>> "remove brick commit" is the issue. Can you please paste your 
>>> command as per the time line of events. That would make it more clear.
>>>
>>> Below are the steps, I do to replace a brick and it works for me.
>>>
>>> |
>>>
>>>  1. |gluster volume add-brick /|VOLNAME NEW-BRICK|/|
>>>  2. |gluster volume remove-brick |VOLNAME|/|BRICK|/| |start|
>>>  3. |gluster volume remove-brick |VOLNAME|/|BRICK|/||status|
>>>  4. |gluster volume remove-brick |VOLNAME /BRICK/| commit|
>>>
>> I will also suggest you to use distribute-replicate volumes, so that 
>> you have a replica copy always and it reduces the probability of 
>> losing data.
>>
>> -Lala
>>
>> _______________________________________________
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>> http://supercolony.gluster.org/mailman/listinfo/gluster-users
>

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