[Gluster-users] Avoiding Split Brains

[Diego Remolina]

Read carefully the blog from JoeJulian, it tells you how to identify
and clear the files in split brain. Make sure you have good backups
prior to erasing anything.

https://joejulian.name/blog/fixing-split-brain-with-glusterfs-33/

He even provides a script.

Diego

On Fri, Oct 30, 2015 at 10:08 AM, Iain Milne <glusterfs at noognet.org> wrote:
> Ok, thanks - that certainly helps (a lot!), but what about all these gfid
> files? Are they files in split-brain or something else? The links don't
> cover dealing with anything like this :-(
>
> My impression is that maybe they're files have haven't replicated and/or
> haven't been self healed, for whatever reason...
>
>> -----Original Message-----
>> From: Diego Remolina [mailto:dijuremo at gmail.com]
>> Sent: 30 October 2015 12:58
>> To: Iain Milne
>> Cc: gluster-users at gluster.org List
>> Subject: Re: [Gluster-users] Avoiding Split Brains
>>
>> Yes, you need to avoid split brain on a two node replica=2 setup. You
> can just
>> add a third node with no bricks which serves as the arbiter and set
> quorum to
>> 51%.
>>
>> If you set quorum to 51% and do not have more than 2 nodes, then when one
>> goes down all your gluster mounts become unavailable (or is it just read
> only?).
>> If you run VMs on top of this then you usually end up with paused/frozen
> vms
>> until the volume becomes available again.
>>
>> These are RH specific docs, but may help:
>>
>> https://access.redhat.com/documentation/en-
>> US/Red_Hat_Storage/2.0/html/Administration_Guide/sect-User_Guide-
>> Managing_Volumes-Quorum.html
>>
>> https://access.redhat.com/documentation/en-
>> US/Red_Hat_Storage/3/html/Administration_Guide/sect-Managing_Split-
>> brain.html
>>
>> First time in testing I hit split brain, I found these blog very useful:
>>
>> https://joejulian.name/blog/fixing-split-brain-with-glusterfs-33/
>>
>> HTH,
>>
>> Diego
>>
>> On Fri, Oct 30, 2015 at 8:46 AM, Iain Milne <glusterfs at noognet.org> wrote:
>> > Anyone?
>> >
>> >> -----Original Message-----
>> >> From: gluster-users-bounces at gluster.org [mailto:gluster-users-
>> >> bounces at gluster.org] On Behalf Of Iain Milne
>> >> Sent: 21 October 2015 09:23
>> >> To: gluster-users at gluster.org
>> >> Subject: [Gluster-users] Avoiding Split Brains
>> >>
>> >> Hi all,
>> >>
>> >> We've been running a distributed setup for 3 years with no issues.
>> >> Recently we switched to a 2-server, replicated setup (soon to be a 4
>> >> servers) and keep encountering what I assume are split-brain
>> >> situations,
>> >> eg:
>> >>
>> >>     Brick server1:/brick
>> >>     <gfid:85893940-63a8-4fa3-bf83-9e894fe852c7>
>> >>     <gfid:8b325ef9-a8d2-4088-a8ae-c73f4b9390fc>
>> >>     <gfid:ed815f9b-9a97-4c21-86a1-da203b023cda>
>> >>     <gfid:7fdbd6da-b09d-4eaf-a99b-2fbe889d2c5f>
>> >>     ...
>> >>     Number of entries: 217
>> >>
>> >>     Brick server2:/brick
>> >>     Number of entries: 0
>> >>
>> >> a) What does this mean?
>> >> b) How do I go about fixing it?
>> >>
>> >> And perhaps more importantly, how to I avoid this happening in the
> future?
>> >> Not once since moving to replication has either of the two servers
>> >> been
>> > offline
>> >> or unavailable (to my knowledge).
>> >>
>> >> Is some sort of server/client quorum needed (that I admit I don't
>> >> fully understand)? While high-availability would be nice to have,
>> >> it's not
>> > essential -
>> >> robustness of the data is.
>> >>
>> >> Thanks
>> >>
>> >> Iain
>> >>
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>> >
>> >
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>
>
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