Re: Quorum Disk Question

From: konabear (maurert_at_ameritech.net)
Date: 03/31/04 

Date: Wed, 31 Mar 2004 14:46:50 GMT

I didn't say that the system disk isn't shared. I said that if there is no
mirrored disk to become the quorum disk, and if the system disk isn't
shadowed. And yes, agreed, if the system disk is being served by a single
node, then there's no need to make that the quorum disk.

For reliability sake, I'm going to prefer a controller based redundant disk
of some sort as the quorum disk. If now mirroring then...

If no shadowing of the system disk, then the system disk is a candidate for
use as a quorum disk. If the system disk is lost, then so is the cluster.
Making the system disk the quorum disk doesn't help or hurt reliability.
Using a nonsystem disk adds one more component that could fail.

"Nic Clews" <sendspamhere@[127.0.0.1]> wrote in message
news:c4bikn$nm$1@lore.csc.com...
> Z wrote:
> >
> > konabear <maurert@ameritech.net> wrote:
> > : If the there is no mirroring and no shadowing then the system disk is
> > : arguably a good candidate for the quorum disk and using it for the
quorum
> > : disk doesn't introduce a new point of failure.
> >
> > I don't understand ... why have a quorum disk at all if it's
> > a device that's not shared?
> >
> > Why not just give the node with the system disk (that you're
> > thinking of making your quorum disk) an extra vote?
>
> That is suggested in the VMS documentation set, so correct observation.
> If only one system is capable of servicing the quorum disk's vote, then
> better give the vote to the system.
>
> So, for the original questioner, you can see why a lowly quorum system
> (typically workstation) is often chosen.
>
> However the "dependency" issue is an interesting one. e.g. the quorum
> disk could be the one with the cluster shared files such as UAF, Que
> files, that sort of thing. Theoretically, without that disk, the cluster
> can't do much (no-one properly log in etc.) There is nothing to stop you
> taking those files off the system disk. Protecting or otherwise those
> files in a hardware raidset of some form is a decision taken locally.
>
> --
> Regards, Nic Clews a.k.a. Mr. CP Charges, CSC Computer Sciences
> nclews at csc dot com

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