Hello rick,
you should define your estimated capacity in the deviceclass as 2000MB.
Your +_800MB for 3490E is also OK. To my knowledge this depends on client
compression. If you have clientcompression on IDRC can't compress it any
more when the data move to tape and ADSM thinks has put 800MB on a tape.
When you don't use client compression IDRC compresses the data when it
put's them on tape and ADSM thinks it has put 2000MB  on a tape. So what it
comes down to is that it is the same amount of userdata only the
compression is at a different place in the chain.
As to the second question it depends on the number concurrent migration
processes and if you are using collocation ore not.
greetings. Koen.



Koen Leeten
Cem
kleeten AT cem DOT be