I've done some experimentation. So far, I've found that TSM will not backup a filesystem image for a fs mounted from /dev/fssnap/N, but it will backup the image as a raw image. This then raises the question of consistency -- making sure that a given filesystem is backed up with the same name every time.
As an example, suppose I have three filesystems (A, B, and C) that I want to backup as an image using fssnap. If I create a snapshot for A, it will be given the snapshot device /dev/fssnap/0. If I then back it up and delete the snapshot, and then create another snapshot for filesystem B, filesystem B will also get the fssnap device /dev/ fssnap/0. Conversely, if I create a snapshot for filesystems A and B concurrently, they will be given different numbers. (0 and 1). Subsequent creations of snapshots will give them the same numbers as they were given in the first instance (so if filesystem A has no snapshot, and I ask for B to have a snapshot created, it will be given /dev/fssnap/1 -- not 0.) I have not experimented beyond two simultaneous filesystems as yet. Based upon my experimentation and reading of the manuals, I get the feeling that there is no way to tell TSM, "Back up this device, but name it as /foo/bar rather than /baz/bam". Can anybody shed any light that may be of use in backing up filesystems in this manner, whilst keeping it clear enough that we can easily determine which device is associated with a given filesystem, and that this mapping is kept consistent? Am I wrong? If not, I fear that this technique will be rendered useless to us. There are other options that I can pursue, as I've indicated before, and I'm about to start on them; I was hoping that the collected TSM gurus might be able to point me in another direction that I haven't yet noticed. The other option, of course, is to ask IBM to support fssnap in a future release, but since that's not likely to happen before 5.4 (at a guess) ... Thanks for all advice that you can give, Stuart.
