Hi Paul:
Yes, my understanding of co-location agrees with yours, but we in fact do have 
more tapes than nodes and a pool of scratch tapes. Our 1st backups on the NT 
side are to disk based storage which are migrated to the tape library storage 
pool where co-location is in effect. During that process there are multiple 
mounts and my assumption until checking was that co-location was occurring by 
node.

We do have nodes that have more data than can be held on one cartridge, but 
again, my assumption would be that another cartridge would be added from the 
scratch pool.

Larry Clark

>>> vkm AT CORNELLC.CIT.CORNELL DOT EDU 04/25/00 04:09PM >>>
At 03:48 PM 4/25/2000 -0400, you wrote:
>Hi:
>I'm puzzled. We have a storage pool with co-location set on, yet after
querying the volume usage table it suggest more than one node is stored on
a given volume. Anyone hazard a guess as to why?

Hi Larry,
  Collocation does not guarantee that only one node will be stored per
volume.  For example, if you have more nodes than volumes, then ADSM will
have to put multiple nodes on a volume.  What collocation does is to strive
to collocate data from one node on as few volumes as possible.  This is
implemented during migration, reclamation, and move data.  When an output
volume is selected by one of these processes, it will preferrentially
select a volume that already has data from that node on it.
  If you happen to have more tapes than nodes, and no node fills more than
one tape, then you will only see 1 node per tape.

..Paul


--
Paul Zarnowski                         Ph: 607-255-4757
Paul Zarnowski                         Ph: 607-255-4757
747 Rhodes Hall, Cornell University    Fx: 607-255-8521
Ithaca, NY 14853-3801                  Em: psz1 AT cornell DOT edu