>> On Fri, 21 Apr 2006 12:47:12 -0700, "Gill, Geoffrey L." <GEOFFREY.L.GILL AT 
>> SAIC DOT COM> said:

> I'm a little confused as to how data is migrated to tape with
> collocation groups configured. Let's say I have 2 collocation groups
> in a single domain each with 10 computers, and I have configured the
> disk pool to migrate using 8 processes, how many processes should I
> see migrating data?

You'd see 2; one for each group.


> What I seem to see is just 2 processes so I'm wondering what is the
> best way to configure the system to migrate quickly yet keep groups
> of computers together. I don't want to collocate each node on it's
> own tape but I do want to take advantage of migrating data with as
> many drives as possible.


You're going to have to find where your sweet spot is between
utilization and collocation.   But consider:

Say your nodes are A0-A9 and B0-B9 (2 groups, 10 nodes each)

If you want the 10 A nodes to use multiple drives, you are also
saying, in a way, that you don't want them collocated (on the minimum
number of tapes).

Perhaps what this means is that you want 4 groups, or 5.




I'm working on a considered theory of collocation group membership,
but the best I've got so far is trying to make the groups' total
occupancy tend towards about 2 volumes' size.



- Allen S. Rout