I don't know why but sometime format cannot get the info from the disk. you can get the info yourself, if your disk is c0t0d0, then run:
pfexec fdisk -G /dev/rdsk/c0t0d0s2 and you will see the geometry of the disk. The output shows you all info that will be asked PS: -> number of usable cylinders = available cylinders - 2 -- This message posted from opensolaris.org
