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I read somewhere that using shared disks for heartbeats is reliable even if network totally fails.
I read it in the context of remedy from split-brain.
Is this correct? But I can not understand this. If network fails, doesn't this also affect shared disks?

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up vote 5 down vote accepted

If by shared disk you mean a LUN mapped to 2 servers from the SAN, then yes - you can use a LUN as the quorum disk. If you use iSCSI for your SAN and the network equipment used for your iSCSI fails, well then your quorum will fail as well.

However, adding a quorum disk and using the same network as you use for your production and heartbeat is very stupid - these should be 3 different networks.

In the environment I have been working with Linux clustering there were 3 ways for the machines in the cluster to communicate:

  • Production network
  • Heartbeat network (separate from prod)
  • Quorum disk (fibre channel)

I hope that this is what you were looking for :)

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So the idea is to use different communication links?That is what you mean by different network? – user76678 Dec 1 '12 at 18:47
Also I am not sure what you mean by fibre channel.I work in SW so setting up these components is not known to me – user76678 Dec 1 '12 at 19:05
@user76678, when you are unfamalier with a term you can usually find a definition with a quick Google search. Not performing your own searches makes you start to seem like a help vampire. – Zoredache Dec 1 '12 at 20:39
@Zoredache:Fair point.It is just that I am not a hw-tech guy and acronyms like these are not know to me.I mean this answer is not as easy to understand (at least on the first couple of readings) for some one with no admin background – user76678 Dec 1 '12 at 21:09
I am not trying to patronise you in any way, but the technologies I mention are pretty standard in most data centers - maybe with exception of Fibre Channel as a lot of places use ISCSI or inifiniband. But if I were you, I would put much effort into learning some more about storage and network infrastructure before messing around with HA clusters. You will burn your fingers if you try to do HA without the proper knowledge about the underlying infrastructure. – Frands Hansen Dec 1 '12 at 21:23

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