A second instance increases complexity and therefore increases
management effort. So the preferred state would be to stay with one
instance if you can do so without problems. If you can fit all of your
daily activities (e.g. backup, migration, TSM db backup, expiration,
reclamation) in a single 24-hour period, then there's really no need to
add a second instance. If the length of one or more of these activities
causes you to not finish your daily activities within a 24-hour period,
then you should do what you can to make that activity faster first,
before splitting your instance.
Is backing up to disk taking too long? Perhaps you need faster disk or
more CPU/RAM for TSM.
Is backing up the disk pool to tape take too long? Again, maybe you
need faster disk; maybe you need more/faster tape drives (or more/faster
CPU/RAM).
Is expiration taking too long? Perhaps you need more CPU/RAM.
Reclamation taking too long? Maybe you need more/faster tape drives;
maybe you need more/faster CPU/RAM. If reclamation is being slowed down
because you don't have enough tape drives, adding a second instance
won't help if it's sharing the same tape drives.
Another thing to consider is whether or not you're giving TSM too much
to do at one time. There was a good discussion last week called
"Spanking my data" that discussed the benefits and drawbacks to doing
multiple TSM tasks simultaneously. (Read it at
http://tinyurl.com/yrpde3 .) TSM will perform better if you have it do
daily activities serially rather than simultaneously. (But, as you will
see in that discussion, that's not always possible.)
SO, if you've done your best to serialize your activities, bought
more/faster CPU/RAM and more/faster tape drives, and you still can't fit
anything within 24 hours, then it's time to split the instance.
The short answer is that most people find that happens when your
database gets well beyond 100 GB -- although not always. I've talked to
people with larger databases that still fit their activities into a
24-hour day. Don't split your instance just because you're at 150 GB.
Split it because you can't get your work done in a 24-hour period and
you've already tried everything else.
---
W. Curtis Preston
Backup Blog @ www.backupcentral.com
VP Data Protection, GlassHouse Technologies
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Lamb, Charles P.
Sent: Monday, January 21, 2008 11:04 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: [ADSM-L] 2ND TSM Instance Question
Hi..........
What is the criteria that tells a person that a 2nd TSM instance is
needed?? Our TSM consultant is saying we are close to needing a 2nd TSM
instance since our DB has 23+ million pages. The DB backup runs about
35 minutes.
Our TSM System is as follows:
AIX 5.3 ML7 SP1
TSM 5.3.4.2
IBM 9133-55A 4-WAY w/16GB of memory
IBM 3584-L32/D32 w/14-LTO2 tape drives directly FC connected
IBM FAStT700 with 1GB SAN using 3TB for DB, log and disk cache
IT Management has authorized having a 8-way RISC w/64GB of memory, 2GB
SAN system and replacing the LTO2 with LTO3 tape drives/LTO3 tapes.
Doesn't a 2nd instance cause 2 operational schemes (on-site and off-site
tapes) of two TSM systems??
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