There is a presentation on the Tivoli website comparing 3590, 9840, LTO, and
DLT.
http://www.tivoli.com/news/press/analyst/tsm.pdf

I agree with Jeff & Dwight;
if you are used to 3590, consider that LTO is a competitor to DLT, not a
competitor to the 3590.

I would base the decision on load:

If your load is less than 20 GB per night, 3590 may be overkill and LTO
might provide a less expensive alternative.

But the larger your load gets, the more abuse your media gets and the more
you need the big iron....

(If you do decide to migrate, it's not a big deal.  You can do it real time.
Hook up the new library to your TSM server. Define new tape storage pools,
and point your management classes or disk migration to the new tape storage
pools.  Then just start running MOVE DATA from your old tape volumes to your
new tape pools.  Backups will continue while it's going on.  If you need a
restore in the meantime, TSM will find the data and mount whichever tapes it
needs.  When the old tapes are all empty, remove the old robot.)

************************************************************************
Wanda Prather
The Johns Hopkins Applied Physics Lab
443-778-8769
wanda_prather AT jhuapl DOT edu

"Intelligence has much less practical application than you'd think" -
Scott Adams/Dilbert
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