I agree that the 2 relevant criteria are
1) can you get everything you need done in a 24 hour period and
2) how long is it going to take your to restore your DB if you have to?

Generally if you can back it up in 35 minutes, assume it will take 70 min to
restore (not including the time to format the space).  Even better, grab a
test box somewhere and TEST how long your restore takes in your
environment.  I think 35 min for DB backup is quite modest and no reason to
split the DB.

The answer to your 2nd question is yes, a 2nd instance gives you 2 separate
TSM servers, just as though they were on 2 physically separate machines;
plus you will need to implement library sharing, etc.  Avoid that complexity
as long as it is practical to do so.

FWIW, before you spend the $$ on an 8-way, do some monitoring with TOPAS "C"
to see how many of your 4 processors are currently in use.  4 faster
processors might very well be enough.


On 1/21/08, Lamb, Charles P. <cplamb AT nppd DOT com> wrote:
>
> 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??
>