EMC – Boot from SAN MSCS Cluster configuration

Disclaimer: I haven’t done a Windows-based CLARiiON host-attach activity in about 4 or 5 years. And it’s been a bit longer than that since I did boot from SAN configurations. So you can make of this what you will. We’ve been building a Windows 2008 R2 Boot from SAN cluster lately. We got to the point where we were ready to add the 60+ LUNs that the cluster would use. The initial configuration had 3 hosts in 3 storage groups with their respective boot LUNs. I had initially thought that I’d just create another Storage Group for the cluster’s volumes and add the 3 hosts to that. All the time I was trying to remember the rule about multiple hosts or multiple LUNs in a Storage Group. And of course I remembered incorrectly.

To get around this issue, I had to add each LUN (there are about 67 of them) to each Storage Group for the cluster nodes. And ensure that they had consistent host IDs across the Storage Groups. Which has worked fine, but isn’t, as Unisphere points out, recommended. There’s also an issue with the number of LUNs I can put in a Consistency Group (32) – but that’s a story for another time.

VMware ESX Cluster in a Box

This is very old news, but one of the neat things about ESX is that you can build clusters for testing and don’t have to shell out for a split-bus DAS or SAN space. My colleague, who’s been using ESX for good and evil (testing Veritas Cluster Server) needed to build one in our dev environment the other day. Last time I did this was to cluster VirtualCenter 2.0.2 and I was a bit rusty on the process.

So, for my reference, do this:

Create a shared vmdk to act as the quorum disk using vmkfstools (it needs to be in thick format)

vmkfstools -c 512m -a lsilogic -d thick /vmfs/volumes/datastore/quorum.vmdk

-c to create a vmdk and what size it should be
-a to specify the adapter type (lsilogic or buslogic)
-d can specify some neat things, like RDM settings, etc

Make another vmdk if you’d like to, well, share some data between the nodes.

Add the disk to the guest as an existing device and change the SCSI ID of the card to something like SCSI (1:0). This adds another SCSI adapter to the guest. Set the sharing mode on the adapter virtual or physical, depending on whether you want the cluster in the box or sharing with another physical / virtual host outside of the ESX host. If you don’t specify the -a option when you create the vmdk, it defaults to buslogic. Obviously if you want to share the disk with another physical host you can’t use a vmdk.

Do the same on the other guest / physical host / etc. Install MSCS or VCS or whatever passes as a clustering solution in your life. Enjoy. I also recommend the man page for vmkfstools – it’s an invaluable reference.