I'll bite... let me throw in my two cents worth:

1.  A 30GB TSM database is considered large.  We have a 30Gb TSM database
with 250 server nodes containing 70TB of data on an IBM 3584 Tape Library.
We have a 5GB log file and process approximately a TB a day in daily
changes.  This is all under the AIX platform, I think it is technically
possible to do it with NT, but the stability and recovery times may be
larger than the AIX platform.  (Our configuration:  2-way, Silvernode, 2GB
memory, SP Switch, 100TX, TSM V. 4.2.2, Fiber attached library/tape drives.

2.  An undersized library usually means you have a lot of "media waits"
while the tape drives fight for contention and available scratch tapes, or
slots.  This usually shows itself immediately with reclamation, migration,
data moves, etc.  If you can't run your scheduled reclamation and still make
your backup window for your scheduled jobs, then you probably need more tape
drives or a larger library.  Check your policies and retention periods.  As
is true with all TSM installations, your mileage may vary.

3.  We just did a disaster/recovery test at a remote site this past weekend
and here is at what we experienced.  The incremental backups worked fine,
the archive backup worked fine, the backupset did not.  We used the archive
tape and rolled forward to point-in-time restore to our disaster recovery
point.  We used Sysback/6000 to recovery the AIX servers with great
results... I highly recommend it.

4.  We are going to a second TSM server on AIX to start backing up key NT
workstations.  We have 9,000 seats but will probably only backup a small
percentage of IT, Finance, and administrative workstations.  We have an old
DLT tape library which we are redeploying for workstation use.  You might
want to consider the same thing with your old tape library as you consider
your purchase of a new one.

5.  Mixed library media on a TSM server is supported.  It should work just
fine.  We are running DLT and LTO tape libraries on a single AIX server for
the past year.  No problem.

Although TSM Server supports both NT and AIX platforms, and I have worked
with both, I have found AIX to be quicker to recover from and more reliable
of the two.  (No, I am not getting paid money from IBM or Microsoft for my
endorsement.  Just one man's opinion ...)

George Cardoza
Perot Systems
310.423.1670 - Office