Obviously in a disaster, if the SAN box is uncontactable for some reason, then you'll not be able to see what is/was on it. For this reason we occasionally take a snapshot of their contents at: /afs/inf.ed.ac.uk/group/services-unit/SAN/web/
There is also the AFSPartitions page, but that only covers AFS partitions, and a single SAN volume may contain multiple partitions.