[Linux-HA] quorumd - is anyone using it?

[b52 at entrap.de]

>  >-------- Îðèãèíàëíî ïèñìî --------
>  >Îò:  b52 at entrap.de
>  >Îòíîñíî: Re: [Linux-HA] quorumd - is anyone using it?
>  >Äî: linux-ha at lists.linux-ha.org
>  >Èçïðàòåíî íà: Ñúáîòà, 2008, Ìàðò 1 13:30:28 EET
>  >----------------------------------
>  >
>  >> Hi all,
>  >>
>  >> is anyone actually using the quorum daemon?
>  >>
>  >> My assessment seems to suggest that it is not workable in any
> scenario;
>  >> but maybe I have missed something?
>  >>
>  >> If not and I'm right, I am afraid that users might actually deploy it,
>  >> thinking it solves something and then be very upset when it fails
> under
>  >> fire. Possibly, the prudent action at this time is to disable it from
>  >> the package and build by default, until it is completed.
>  >
>  >I thought it is essential for any cluster with an even amount of nodes?
>  >How would you decide DR in a split-brain condition of two nodes without
> a
>  >quorum server? Is it possible?
>
>
> Yes, is possible. If you have 2 nodes just join a third node to the
> cluster without running any resources on it. There you go you have quorum
> without quorum server.
>
> I beleive the quorum server idea is not that simple to use it only when
> you have even number of nodes. Quorum server should be used in DR when you
> have 2 separate data centers. Quorum server must decide which site is down
> and grant quorum to the other one, even if it has less nodes.
>
> Imagine you have 5 nodes cluster. 3 nodes in site A, 2 nodes in site B.
> Network between both sites is down so site A has majority quorum thus
> continue to run the service. But what happens if site A is down? Site B
> must takeover the sevice but it has not majoroty quorum - 2 nodes only!
>
> Here comes the Quorum server. Site B contacts the quorum server (change in
> membership is detected). Quorum server has lost connection to the site A
> therefore it grants quorum to site B.
>
> Unfortunatelly Quorum server does not work in 2.1.3. I hope it get fixed
> ASAP.

Hm okay and what if the uneven node (3. or 5. or 7...) is off for
maintenance. I am having an even node cluster again with the possibility
of an evil even split-brain condition..
Is there no reliable way to solve this? Because of that I thought its the
job of the quorum server.

Cheers,
Holger

> Regards,
> Atanas
>
>
>  >
>  >Cheers,
>  >Holger
>  >
>  >> Regards,
>  >>     Lars
>  >>
>  >> --
>  >> Teamlead Kernel, SuSE Labs, Research and Development
>  >> SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nürnberg)
>  >> "Experience is the name everyone gives to their mistakes." -- Oscar
> Wilde
>  >
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