[Gluster-users] Does replace-brick migrate data?

[Ravishankar N]

On 29/05/19 3:59 AM, Alan Orth wrote:
> Dear Ravishankar,
>
> I'm not sure if Brick4 had pending AFRs because I don't know what that 
> means and it's been a few days so I am not sure I would be able to 
> find that information.
When you find some time, have a look at a blog <wp.me/peiBB-6b> series I 
wrote about AFR- I've tried to explain what one needs to know to debug 
replication related issues in it.
>
> Anyways, after wasting a few days rsyncing the old brick to a new host 
> I decided to just try to add the old brick back into the volume 
> instead of bringing it up on the new host. I created a new brick 
> directory on the old host, moved the old brick's contents into that 
> new directory (minus the .glusterfs directory), added the new brick to 
> the volume, and then did Vlad's find/stat trick¹ from the brick to the 
> FUSE mount point.
>
> The interesting problem I have now is that some files don't appear in 
> the FUSE mount's directory listings, but I can actually list them 
> directly and even read them. What could cause that?
Not sure, too many variables in the hacks that you did to take a guess. 
You can check if the contents of the .glusterfs folder are in order on 
the new brick (example hardlink for files and symlinks for directories 
are present etc.) .
Regards,
Ravi
>
> Thanks,
>
> ¹ 
> https://lists.gluster.org/pipermail/gluster-users/2018-February/033584.html
>
> On Fri, May 24, 2019 at 4:59 PM Ravishankar N <ravishankar at redhat.com 
> <mailto:ravishankar at redhat.com>> wrote:
>
>
>     On 23/05/19 2:40 AM, Alan Orth wrote:
>>     Dear list,
>>
>>     I seem to have gotten into a tricky situation. Today I brought up
>>     a shiny new server with new disk arrays and attempted to replace
>>     one brick of a replica 2 distribute/replicate volume on an older
>>     server using the `replace-brick` command:
>>
>>     # gluster volume replace-brick homes wingu0:/mnt/gluster/homes
>>     wingu06:/data/glusterfs/sdb/homes commit force
>>
>>     The command was successful and I see the new brick in the output
>>     of `gluster volume info`. The problem is that Gluster doesn't
>>     seem to be migrating the data,
>
>     `replace-brick` definitely must heal (not migrate) the data. In
>     your case, data must have been healed from Brick-4 to the replaced
>     Brick-3. Are there any errors in the self-heal daemon logs of
>     Brick-4's node? Does Brick-4 have pending AFR xattrs blaming
>     Brick-3? The doc is a bit out of date. replace-brick command
>     internally does all the setfattr steps that are mentioned in the doc.
>
>     -Ravi
>
>
>>     and now the original brick that I replaced is no longer part of
>>     the volume (and a few terabytes of data are just sitting on the
>>     old brick):
>>
>>     # gluster volume info homes | grep -E "Brick[0-9]:"
>>     Brick1: wingu4:/mnt/gluster/homes
>>     Brick2: wingu3:/mnt/gluster/homes
>>     Brick3: wingu06:/data/glusterfs/sdb/homes
>>     Brick4: wingu05:/data/glusterfs/sdb/homes
>>     Brick5: wingu05:/data/glusterfs/sdc/homes
>>     Brick6: wingu06:/data/glusterfs/sdc/homes
>>
>>     I see the Gluster docs have a more complicated procedure for
>>     replacing bricks that involves getfattr/setfattr¹. How can I tell
>>     Gluster about the old brick? I see that I have a backup of the
>>     old volfile thanks to yum's rpmsave function if that helps.
>>
>>     We are using Gluster 5.6 on CentOS 7. Thank you for any advice
>>     you can give.
>>
>>     ¹
>>     https://docs.gluster.org/en/latest/Administrator%20Guide/Managing%20Volumes/#replace-faulty-brick
>>
>>     -- 
>>     Alan Orth
>>     alan.orth at gmail.com <mailto:alan.orth at gmail.com>
>>     https://picturingjordan.com
>>     https://englishbulgaria.net
>>     https://mjanja.ch
>>     "In heaven all the interesting people are missing." ―Friedrich
>>     Nietzsche
>>
>>     _______________________________________________
>>     Gluster-users mailing list
>>     Gluster-users at gluster.org  <mailto:Gluster-users at gluster.org>
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>
>
>
> -- 
> Alan Orth
> alan.orth at gmail.com <mailto:alan.orth at gmail.com>
> https://picturingjordan.com
> https://englishbulgaria.net
> https://mjanja.ch
> "In heaven all the interesting people are missing." ―Friedrich Nietzsche
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