Gluster users - Apr 2019 - Is "replica 4 arbiter 1" allowed to tweak client-quorum?

Hi All,

I had a replica 2 cluster to host my VM images from my Proxmox cluster.
I got a bit around split brain scenarios by using "nufa" to make sure
the files are located on the host where the machine also runs normally.
So in fact one replica could fail and I still had the VM working.

But then I thought about doing better and decided to add a node to
increase replica and I decided against arbiter approach. During this I
also decided to go away from nufa to make it a more normal approach.

But in fact by adding the third replica and removing nufa I'm not really
better on availability - only split-brain-chance. I'm still at the point
that only one node is allowed to fail because else the now active client
quorum is no longer met and FS goes read only (which in fact is not
really better then failing completely as it was before).

So I thought about adding arbiter bricks as "kind of 4th replica (but
without space needs) ... but then I read in docs that only "replica 3
arbiter 1" is allowed as combination. Is this still true?
If docs are true: Why arbiter is not allowed for higher replica counts?
It would allow to improve on client quorum in my understanding.

Thank you for your opinion and/or facts :-)

Ingo

Hi,

I guess you missed Ravishankar's reply [1] for this query, on your previous
thread.
[1] https://lists.gluster.org/pipermail/gluster-users/2019-April/036247.html

Regards,
Karthik

On Wed, Apr 10, 2019 at 8:59 PM Ingo Fischer <ingo at fischer-ka.de>
wrote:
> Hi All,
>
> I had a replica 2 cluster to host my VM images from my Proxmox cluster.
> I got a bit around split brain scenarios by using "nufa" to make
sure
> the files are located on the host where the machine also runs normally.
> So in fact one replica could fail and I still had the VM working.
>
> But then I thought about doing better and decided to add a node to
> increase replica and I decided against arbiter approach. During this I
> also decided to go away from nufa to make it a more normal approach.
>
> But in fact by adding the third replica and removing nufa I'm not
really
> better on availability - only split-brain-chance. I'm still at the
point
> that only one node is allowed to fail because else the now active client
> quorum is no longer met and FS goes read only (which in fact is not
> really better then failing completely as it was before).
>
> So I thought about adding arbiter bricks as "kind of 4th replica (but
> without space needs) ... but then I read in docs that only "replica 3
> arbiter 1" is allowed as combination. Is this still true?
> If docs are true: Why arbiter is not allowed for higher replica counts?
> It would allow to improve on client quorum in my understanding.
>
> Thank you for your opinion and/or facts :-)
>
> Ingo
> _______________________________________________
> Gluster-users mailing list
> Gluster-users at gluster.org
> https://lists.gluster.org/mailman/listinfo/gluster-users
>
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