==> On Mon, 5 Dec 2005 16:33:43 -0500, "Spearman, Wayne" <[EMAIL PROTECTED]> said:
> We are planning to move a large number of our nodes to "disk only" backups > and eliminate tape for them. The diskpools will be devtype=file. I struggle > with whether to collocate these disk volumes or not and how large to make > them. I've had some discussions with IBM, but would like to ask others to > share their experiences with me. For collocation, my question would be 'Why ever not?' If you've got N machines backing up simultaneously, you'll have N files open; I'd say pick the "correct" N. As for size, My aesthetic opinion on this is that they should be substantially smaller than 1% of the enclosing capacity. So if you've got a 1TB of space, I think a 10GB volume is too big. The last time I actually picked a number, we had ~8TB of space, and I picked a 5GB volume size. This meant that my reclamation was happening in what felt like manageable chunks, and if I wanted to actually move things around I could do so on a sane granularity. The other force on volume size is "I don't want to have too many to manage". I'll assert that once you get into disk-only backups, you're going to have a volume count which you will -need- to manage in an automated fashion. So you _will_ be writing scripts to do things, instead of typing e.g. "move data" commands at the TSM> prompt. SO since you've already lost the manual-operation battle, you may as well go for the "reasonaby small" win. Keep in the back of your mind that backupsets are portable; if you write a backupset to disk, and then copy it somewhere else, you can use it indefinitely. So the FILE storage might be accessed from somewhere other than thru TSM. - Allen S. Rout
