>> On Fri, 18 Aug 2006 12:30:08 -0400, "Kauffman, Tom" <[EMAIL PROTECTED]> said:
> TSM will mount and start as many sessions as possible, and the rest will > be in 'wait media' state until the tape they need (or a tape drive) > becomes available. Given your scenarion, you may have one session > reading tape and the other four waiting for access to the same tape. > When the first session has retrieved ALL the files it needs from the > first tape, it will go to the second (if not in use) and the session > that has been waiting the longest will now get access to that first > tape. Several important points: The session that has been waiting the longest will get access to the tape -drive-, and if the longest-waiting session desires the mounted tape, that's all good. But the chances of that aren't great: each restore will calclulate its' list of desired tapes and its' desired order independantly, and each one will walk through that order linearly. Period. (last time I checked). This means that if hosts A and B both want tapes T0 and T1, and they both pick that order, and A gets T0 first, B will not fall back to deal with T1 before it blocks on T0 access. That dynamic reordering of work is just not something TSM does at the moment, and I can't blame them too much. Sounds hard in most cases. Implications for the case Troy suggested (5 simultaneous restores, 4 tapes drives, many noncollocated tapes) are that it is extremely unlikely that any mounted tape will be cleanly passed from one restore process to another; transitions will usually require a dismount and a mount. As usual, anyone got evidence that TSM's gotten smarter since last I looked, shoot me down. - Allen S. Rout