[Linux-cluster] Quorum disk over RAID software device
Rafael Micó Miranda
rmicmirregs at gmail.com
Tue Dec 15 19:10:16 UTC 2009
Hi Brem
El mar, 15-12-2009 a las 17:21 +0100, brem belguebli escribió:
> Hi,
>
> The problem you could encounter is the network and storage split brain.
>
> If your Qdsik LUNs were hosted by 2 arrays located in 2 different
> rooms or site, each room hosting half the nodes of your cluster, in
> case a SAN and network partition occurs between the 2 rooms, you'll
> find yourself in a perfect storage and network split brain.
>
> Each room having the same number of nodes and accessing one leg of
> your qdisk, each qdisk leg being seen "alive" by the nodes in the
> room.
>
> Brem
>
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I thought about this. In my situation:
- All the nodes are in the same site.
- All the nodes are connected to the two storage arrays via the same FC
switches in a symmetric way.
- All the nodes have their network interfaces connected to the same
couple of Ethernet Switches in a symmetric way via bonding.
I think the probability of failing exactly the devices that should fail
(5 exact FC ports in one FC switch, another 5 on the another FC switch
and a "split" in the Ethernet switches themselves exactly dividing the
nodes in groups of 3) is pretty small.
I see you exposed your point with the idea of a multi-site cluster with
the 2 qdisk LUNs placed in different sites and cluster nodes in both of
them, but this is not the case. But that is, in fact, a really
interesting scenario :)
Thanks for your interest. Cheers,
Rafael
--
Rafael Micó Miranda
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