>  Has anybody out there gone from 3 years of nocollocation and then
>changed to collocation for better restores.  We are currently at 2-3+ TB of
>info on 540 tapes (this is all in our 1 TAPEPOOL).  We have about 410
>scratch tapes and the uppers are worried about making the global switch to
>collocate will cause TSM to crash due to no scratch tapes.

Bill,
I made this move last year myself. The main thing I had to consider was how
many scratch tapes I had, and extra library slots available, compared to the
number of nodes that were now going to now grab tapes.

I don't know the inner working of TSM related but I can say I planned for
the worst. I may have had any number of tapes in filling status but I went
on the assumption that none were going to be used once co-location was
turned on. For me that meant 180 tapes off the top. I also assumed that over
time reclamation would clean things up and free up tapes, which it did.

For us that was ok because I also had around 400 blank tapes to work from.
Something I've had to keep an eye out for since then though is tapes going
unavailable/read-only. If that happens then the affected node will
automatically grab a new tape. In cases like that I always move the data to
free up that extra tape.

The bottom line is it went off without a hitch.

Geoff Gill
TSM Administrator
NT Systems Support Engineer
SAIC
E-Mail:   gillg AT saic DOT com
Phone:  (858) 826-4062
Pager:   (877) 905-7154