Werner, I feel your pain... ;)
You have hit most of the major issues of disaster recovery with TSM squarely on the head. We have had similar experience in our testing... 4-6 hours to get the TSM server up, running through loads of tapes (even though storage pool is collocated with only three servers), 48-hour window, etc. We have proved that we can get our three critical clients back within 24 hours, but they are not nearly as big as yours. We use DLT8000 drives. Probably the best way for you to get better restore throughput is to add more drives and do concurrent restores. TSM should only mount the tapes that actually contain the file versions you will restore. The problem is that, even with collocation, after many months of backups on a relatively active system, these files will get scattered across many tapes. Conventional wisdom suggests using collocation by filespace to reduce this effect... and also guarantee that concurrent restores of different file systems will not compete for the same tape volume. But the cost is of course using a lot more tape. Another approach might be to occasionally (every three months maybe) do a "full" backup (by changing mode to "absolute" to force even unchanged files to get backed up)... this should effectively "defragment" the tape pool and put all active versions on one (or a couple) tape. We did this once with an additional machine that we DR'ed and it worked quite well. Some people don't like this concept because it defeats TSM's "progressive" backup methodology, but I think its an acceptable compromise. As you said, backup sets are not a good option for DR... for one thing, creating the backupset will take as long as restoring the whole system, and will read the same number of tapes. You will suffer this on a regular schedule since you'll have to make new backupsets probably every week or two. Secondly, restoring from backupsets effectively single-threads that client because all of it's data is on one or maybe two tapes. Good luck, and please keep us posted on your results! Robin Sharpe Berlex Labs
