BM_DISK from BEI, the producers of UltraBac, will test the raw read capability of your disks.

Usage is BM_DISK ┬źDrive#┬╗ where 0 is the 1st disk, 1 is the second disk, etc..

BEI reports that the fastest performance they have seen was from a Compaq raid array which yielded 16 Megabytes/second.