Question about fencing and co-ordinator disks
We're running VCS 4.1 MP2 on Solaris. We have 4 nodes connected via a fibre fabric to 3 arrays. Each one of these arrays has a small LUN and we've put all three of these LUNs in to a fencedg disk group. This is the diskgroup we have in /etc/vxfendg.
This all works well when there are no failures. Today one of our arrays failed so we were down to only 2 disks in our fencing DG. When one of our nodes was rebooted it couldn't start it's fencing driver, which I believe was because only 2 disks were found in the fencing DG.
So I'm wondering how best to solve this. We'll shortly be adding another array so we could then have 4 disks in the DG, but 4 isn't an odd number, so that's out.
If we put 5 disks in the fencing DG (so put 2 on one array, and 1 on the other three), that'd seem to work. Unless an array fails and we get a split brain at the same time, at which point we only have 4 disks and the fight over the co-ordinator disks could tie.
So I'm not really sure what the best course of action is. Any advice?
Thanks guys.
Tim.