[Gluster-users] Directory in split brain does not heal - Gfs 9.2

Sat Sep 3 06:17:40 UTC 2022

I would start by reading the 3 blogs from Ravi:https://ravispeaks.wordpress.com/2019/04/05/glusterfs-afr-the-complete-guide/https://ravispeaks.wordpress.com/2019/04/15/gluster-afr-the-complete-guide-part-2/https://ravispeaks.wordpress.com/2019/05/14/gluster-afr-the-complete-guide-part-3/

All pending heals a hard links created in  .glusterfs/indices/xattrop .Check the attributes of a the gfids there (one by one) for differences  on the bricks and if they are the same - you can delete them from .glusterfs/indices/xattrop (the root entry must stay !!!). If not, the attributes can hint you what happened and which is the good copy.
Best Regards,Strahil Nikolov  
  On Wed, Aug 31, 2022 at 15:30, Ilias Chasapakis forumZFD<chasapakis at forumZFD.de> wrote:    
Hi all,

so we went further and deleted the entries (data and gfid). The split brain is now gone, but when we triggered a heal again (simple and full) we have many entries stuck in healing (no split-brain items). They are there since days/weeks and still appearing.

We would like to heal single files but as they are not in split brain I guess this is not possible right? The "source-brick" technique works only in that case I think?

A concrete example of one of that files that are stuck in the healing queue: I checked the attributes with getfattr and saw that one of the nodes does not have nor the data or the gfid. Missing completely. How could I trigger a replication from the "good copy" to the gluster node that does not have the file? Is it possible for entries *not* in split brain? Doing a listing on the mount side (ls) of the affected directory did not seem to trigger a heal.

Also the shd logs have some ambiguous (for me) entries. The sink value is empty, shouldn´t it be a number indicating it is healing?

[2022-08-28 17:22:11.098604 +0000] I [MSGID: 108026] [afr-self-heal-common.c:1742:afr_log_selfheal] 0-vol-replicate-0: Completed metadata selfheal on 94503c97-7731-4aa1-8a14-2c6ea5a84a15. sources=1 [2]  sinks= 
 [2022-08-28 17:22:16.227091 +0000] I [MSGID: 108026] [afr-self-heal-common.c:1742:afr_log_selfheal] 0-gv-ho-replicate-0: Completed metadata selfheal on 94503c97-7731-4aa1-8a14-2c6ea5a84a15. sources=1 [2]  sinks= 

I try to use the guide here:

https://docs.gluster.org/en/main/Troubleshooting/troubleshooting-afr/#ii-self-heal-is-stuck-not-getting-completed

but find difficult to apply.

Do you have any suggestions on how to "unblock" these stuck entries and what is a methodic approach to troubleshooting this situation?

Finally I would like to ask if the risk of updating the glusters (we have pending updates now) would be too dangerous without previously fixing the unhealed entries. Our hope is that an update could eventually fix the problems.

Best regards.
 Ilias

 Am 18.08.22 um 23:38 schrieb Strahil Nikolov:

 If you refer to/<path_to_brick>/.glusterfs/<gfid_first_2_characters>/<gfid_second_2_characters>/gfid - it' s a hard link to the file on the brick. Directories in the .glusterfs are just symbolic links. 
  Can you clarify what you are planing to delete ? 
  Best Regards, Strahil Nikolov   

  On Wed, Aug 17, 2022 at 14:35, Ilias Chasapakis forumZFD <chasapakis at forumZFD.de> wrote:     
Hi Thomas,

Thanks again for your replies and patience :)

We have also offline backups of the files.

So, just to verify I understood this correctly, deletion of a .glusterfs-gfid file doesn't inherently include the risk of the loss of the complete brick, right?

I saw you already applied this for your purposes so it worked for you... But just as a confirmation. Of course it is fully understood that the operational risk is on our side.

It is just an "information-wise" question :)

Best regards
 Ilias

 Am 17.08.22 um 12:47 schrieb Thomas Bätzler:

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Hello Ilias,

 Please note that you can and should backup all of the file(s) involved in the split-brain by accessing them over the brick root instead of the gluster mount. That is also the reason why you’re not in danger of a failure cascade wiping out our data.

Be careful when replacing bricks, though. You want that heal to go in the right direction 😉

Mit freundlichen Grüßen,

i.A. Thomas Bätzler

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Von: Gluster-users <gluster-users-bounces at gluster.org> Im Auftrag von Ilias Chasapakis forumZFD
 Gesendet: Mittwoch, 17. August 2022 11:18
 An: gluster-users at gluster.org
 Betreff: Re: [Gluster-users] Directory in split brain does not heal - Gfs 9.2

Thanks for the suggestions. My question is if the risk is actually related to only losing the file/dir or actually creating inconsistencies that span through the bricks and "break everything".
 Of course we have to take action anyway for this not to spread (as we already now have a second entry that developed an "unhealable" directory split-brain) so it is just a question of evaluation before acting.

Am 12.08.22 um 18:12 schrieb Thomas Bätzler:

Am 12.08.2022 um 17:12 schrieb Ilias Chasapakis forumZFD:

Dear fellow gluster users,

we are facing a problem with our replica 3 setup. Glusterfs version is 9.2.

We have a problem with a directory that is in split-brain and we cannot manage to heal with:

gluster volume heal gfsVol split-brain latest-mtime /folder

The command throws the following error: "failed:Transport endpoint is not connected." 

So the split brain directory entry remains and and so the whole healing process is not completing and other entries get stuck.

I saw there is a python script available https://github.com/joejulian/glusterfs-splitbrain Would that be a good solution to try? To be honest we are a bit concerned with deleting the gfid and the files from the brick manually as it seems it can create inconsistencies and break things... I can of course give you more information about our setup and situation, but if you already have some tip, that would be fantastic.

You could at least verify what's going on: Go to your brick roots and list /folder from each. You have 3n bricks with n replica sets. Find the replica set where you can spot a difference. It's most likely a file or directory that's missing or different. If it's a file, do a ls -ain on the file on each brick in the replica set. It'll report an inode number. Do a find .glusterfs -inum from the brick root. You'll likely see that you have different gfid-files.

To fix the problem, you have to help gluster along by cleaning up the mess. This is completely "do it at your own risk, it worked for me, ymmv": cp (not mv!) a copy of the file you want to keep. On each brick in the replica-set, delete the gfid-file and the datafile. Try a heal on the volume and verify that you can access the path in question using the glusterfs mount. Copy back your salvaged file using the glusterfs mount.

We had this happening quite often on a heavily loaded glusterfs shared filesystem that held a mail-spool. There would be parallel accesses trying to mv files and sometimes we'd end up with mismatched data on the bricks of the replica set. I've reported this on github, but apparently it wasn't seen as a serious problem. We've moved on to ceph FS now. That sure has bugs, too, but hopefully not as aggravating.
 MfG, i.A. Thomas Bätzler --  BRINGE Informationstechnik GmbH Zur Seeplatte 12 D-76228 Karlsruhe Germany    Fon: +49 721 94246-0 Fon: +49 171 5438457 Fax: +49 721 94246-66 Web: http://www.bringe.de/    Geschäftsführer: Dipl.-Ing. (FH) Martin Bringe Ust.Id: DE812936645, HRB 108943 Mannheim 

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