Alex,
How have you defined FORMAT under DEVICECLASS?
Choose FORMAT=3570C rather than FORMAT=DRIVE when defining your 3570
devices.

Also, is client compression activated on all your clients?  If so, the net
results you see when displaying your volumes will show COMPRESSED data
space.  Even when compression activated on the drive, you won't see much,
if
any, improvement.

Hope it is a simple problem
Randy