RPM vs transfer speed.

ok, here is the issue.

I want to know if SATA II are better than new 15K RPM SCSI drives due the transfer rate, because the RPM is still less on SATA…..

I am unable to find any speed test on raid systems, also unable to find the specific search time on those disks.

This question is in order to choose between the Dell SAN system with 10RPM SATA drives and the normal SAN with 15K RPM SCSI drives (with too high cost).