[Gluster-users] Quorum replica 2 and arbiter

[Pranith Kumar Karampuri]

On Sat, Apr 22, 2017 at 12:48 PM, Pranith Kumar Karampuri <
pkarampu at redhat.com> wrote:

> We are evolving a document to answer this question, the wip document is at
> https://github.com/karthik-us/glusterdocs/blob/
> 1c97001d482923c2e6a9c566b3faf89d0c32b269/Administrator%
> 20Guide/Split%20brain%20and%20ways%20to%20deal%20with%20it.md
>
> Let us know if you still have doubts after reading this.
>
> On Tue, Apr 18, 2017 at 8:41 AM, Mahdi Adnan <mahdi.adnan at outlook.com>
> wrote:
>
>> Hi,
>>
>> We have a replica 2 volume and we have issue with setting proper quorum.
>>
>> The volumes used as datastore for vmware/ovirt, the current settings for
>> the quorum are:
>>
>>
>>
>> cluster.quorum-type: auto
>>
>> cluster.server-quorum-type: server
>>
>> cluster.server-quorum-ratio: 51%
>>
>>
>>
>> Losing the first node which hosting the first bricks will take the
>> storage domain in ovirt offline but in the FUSE mount point works fine
>> "read/write"
>>
>> Losing the second node or any other node that hosts only the second
>> bricks of the replication will not affect ovirt storage domain i.e 2nd or
>> 4th ndoes.
>>
>> As i understand, losing the first brick in replica 2 volumes will render
>> the volume to read only, but how FUSE mount works in read write ?
>>
>> Also, can we add an arbiter node to the current replica 2 volume without
>> losing data ? if yes, does the re-balance bug "Bug 1440635" affect this
>> process ?
>>
>  I remember we had one user in Redhat who wanted to do the same procedure
on his production workload with 3.8.x upstream bits and it worked fine. I
forget which version it was. Ravi, do you remember?


> And what happen if we set "cluster.quorum-type: none" and the first node
>> goes offline ?
>>
> cluster.quorum-type none is equivalent to no quorum, so the file can go
into split-brains/ it can serve stale reads. Please don't do this on 3-way
replica/arbiter volumes unless you know what you are doing.

> Thank you.
>>
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>>
>>
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>
>
>
> --
> Pranith
>



-- 
Pranith
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