What items do I need to ensure I have backed up (to tape) in the event of a true/total DR situation in order to restore my cluster?

I know that I would need to re-create the volumes/mapping on the SAN
I know that I would need to reinstall the SLES OS
I know that I would probably need to reinstall OES (BTW, this is AFTER I have reinstalled my eDir DS Master server which has the .dsbk backup files or whatever via cron job).

Is ALL the necessary cluster info held in eDir for an OES2 cluster?

Or are there other files I should be backing up somewhere (we technically backup the cluster nodes themselves--the SLES partitions)?