[Linux-cluster] Cluster stability with missing qdisk

[emmanuel segura]

Why you don't use qdisk on multipath, than can resolv your problem

2012/2/10 Jan Huijsmans <Jan.Huijsmans at interaccess.nl>

> Hello,
>
> In the clusters we have we use a qdisk to determine which node had the
> quorum, in case of a split brain situation.
>
> This is working great... until the qdisk itself is hit due to problems
> with the SAN. Is there a way to have a stable cluster,
> with qdisks, where the absence of (1) qdisk won't kill the cluster all
> together. At this moment, with the setup with 1 qdisk,
> the cluster is totally depending on the availability of the qdisk, while,
> IMHO, it should be expendable.
>
> We have now a triangle setup, with 2 data centers and 1 extra 'quorum'
> location for the IBM SAN. In the SAN setup there
> are 3 quorum devices, 1 in each data center and the 3rd on the quorum
> location. When 1 location fails (one of the data
> centers or the quorum location) it is still up and running.
>
> Is it possible to copy this setup and use 3 qdisks, so when 1 qdisk fails
> the cluster stays alive? I would set the vote
> value of all components (systems and qdisks) to 1, so the cluster would
> keep running with 2 systems and 1 qdisk
> or 1 system with 2 qdisks. (it'll be dead with only 3 qdisks, as the
> software will die with both systems ;) )
>
> I've heard of setup's with 3 systems, where the 3rd was just for the
> quorum, so you this one can die, but on this
> occasion it won't help us, as there are no systems on the 3rd location.
> (and it's not supported by Red Hat, when I'm
> correctly informed)
>
> With regards,
> Inter Access BV
>
> ing. J.C.M. (Jan) Huijsmans
> Designer / Technical Consultant UNIX & Linux
> Infrastructure Professional Services UNIX
>
> E-mail:  jan.huijsmans at interaccess.nl
>
> Tel:     035 688 8266
> Mob.:    06 4938 8145
>
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