Is it possible to undelete a volume in a HP MSA 2000?
Not entirely true. It is possible but there is no guarantee that it will work. The basic steps are: Recreate the LUN and make sure it is EXACTLY the same size as the delete LUN. Present the LUN to a server and use FDISK or equivalent to recreate the partition.
In my case I was using the LUN on a VMWARE ESXi host and once I had recreated the LUN, I presented this to the ESXi host and used the following article to re-create the partition (setting the start and end blocks of the partition to be EXACTLY the same as it was before the LUN was deleted). See http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2046610
I had to do quite a bit of trial and error on this and the whole process took 3 hours which was a lot quicker than having to try to restore 2TB of data.