I'm sure that customers with more practical experience than I will have
information to offer, but here are my two cents:
Before turning collocation off, consider:
- Even with a fully-automated library, restoring a large number of files
from non-collocated pools may take substantially longer than restoring
from collocated pools.
- While the need for large-scale restores may indeed be rare, when such a
restore situation arises, your users usually want the data back
*yesterday*. Turning off collocation may sound good on paper, but will it
fly when you are actually in a restore situation and you have your users
or management breathing down your neck?
The tape utilization is also a legitimate issue. One way to compromise
would be to figure out which systems are mission-critical and need the
fastest restore capability. These can be backed up to collocated pools,
while noncritical systems can be backed up to non-collocated pools. A
variation could be to offer three levels of service: collocation by file
space (for the most critical systems), collocation by node (for less
critical systems), and no collocation (for noncritical systems). If you
have a chargeback mechanism in place, you could consider modifying it to
increase the cost with degree of collocation. If you have service level
agreements with your users, you should make sure to document the level of
service the client machines will receive.
Regards,
Andy
Andy Raibeck
IBM Software Group
Tivoli Storage Manager Client Development
Internal Notes e-mail: Andrew Raibeck/Tucson/IBM@IBMUS
Internet e-mail: storman AT us.eyebm DOT com (change eye to i to reply)
The only dumb question is the one that goes unasked.
The command line is your friend.
"Good enough" is the enemy of excellence.
Farren Minns <fminns AT WILEY.CO DOT UK>
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
04/07/2003 07:17
Please respond to "ADSM: Dist Stor Manager"
To: ADSM-L AT VM.MARIST DOT EDU
cc:
Subject: Turning collocation off?
Hi All
Running TSM 4.2.2.12 on Sol 2.7 server. At present we use collocation on
the tapes within the TAPEPOOL (i.e. in the 3494 library). We are getting
to
a point where the number of available scratch tapes in the lib is getting
small and I'm considering turning collocation off. We always seem to have
about 25-30 tapes that are under 10% used which seems like a large waste
of
space.
I understand that collocation speeds things up in the event of a system
restore, but this is something that we rarely (in fact, never in the last
two years) need to do and anyway, the library can handle all the tape
mounts and stuff.
This is all rather long winded, but my question is simple. Are there any
things I should be aware of before setting collocation to NO. i.e., are
there any possible problems I may encounter.
Many thanks
Farren Minns - John Wiley & Sons Ltd
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