Hello Paul,
We do this. You can set maxscratch=0 and define private volumes to the
storage pool, or you can set maxscratch=nnn, and use scratch tapes that
way, without using up all of the tapes in your robot. We do the former,
mostly. It is not a problem to have more users than tapes. In fact, as
tape capacities get larger and larger, this is more and more likely to
happen. The thing you need to watch out for, over time, is that your tapes
will eventually fill up. It is important to monitor this and make sure you
have an adequate number of tapes in empty or filling status. If too many
of your tapes fill up, then the remaining tapes will acquire data from more
and more nodes. The problem comes when it becomes time to reclaim those
tapes. If you get too many nodes (or collocation clusters) on a tape, then
the reclaim process will require too many tape mounts. Eventually, you
will find that the reclaim process bogs down on tape mounts. This varies
depending on what type of tape drives you are using. Drives with slower
mount times will suffer more than those with faster mount times. They
point I am trying to make here is don't wait for your tape robot to fill up
before adding tape capacity.
..Paul
At 11:58 AM 1/26/2001 +0100, Paul Baines wrote:
Hello,
We are running a 3494 library serving, among others, some 1400 NT servers.
These servers occupy on average 2 Gb in a non-collocated storage pool. We
want/need to switch on collocation at a node level for these clients, but
I don
t
want to let them collocate on 1400 30-50Gb 3590s. How do people manage the
use of their collocated storage pools? Do you set maxscratch=0 and just define
volumes to the storage pool? What if I ve got 1400 clients and 300 tapes?
Does collocation work properly if you limit the number of tapes?
If I have 2700Gb and 2Gb per client then :
5 clients / tape 10 Gb / tape = 270 tapes
6 clients / tape 12 Gb / tape = 225 tapes
7 clients / tape 14 Gb / tape = 192 tapes
8 clients / tape 16 Gb/ tape = 168 tapes
9 clients / tape 18 Gb / tape = 150 tapes
10 clients / tape 20 Gb / tape = 135 tapes
OK, these are idealised averages, but how are you doing it? How full or how
many clients do you have on collocated storage pool tapes?
Ta in advance for any comments,
Paul.
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