I always thought you would have problems mixing speeds in a raid group. Specifically you would see 'failing servo motor' autosupport messages.
Or are you suggesting raid groups segregated by speed and only mixing speeds within an aggregate made up of the speed based raid groups?
-Matthew
On our R200 the original 320G drives are 5400 RPM. We recently bought two more shelves and these were all 7200 RPM. Since then some 5400 RPM drives have failed and the system has reconstructed on 5400 RPM hot spares. The replacements from Netapp have all been 7200 RPM, so we have no 5400 RPM hot spares any more. We'll find out if mixed speed raid groups work when the next 5400 RPM disk dies :-)
Actually Netapp told us it's not a problem to replace a slower drive with a faster one. It's not good if you have a RG of fast drives to replace one with a slower drive, because that drags down the whole RG.
Steve Losen scl@virginia.edu phone: 434-924-0640
University of Virginia ITC Unix Support