You're right that SCSI is faster than IDE. It's also more scaleable, because you can add many drives to a SCSI RAID array (the specific number of drives you can add varies depending on your hardware). IDE RAID has a nice niche, though. It's MUCH faster than software-based RAID (ie., mirroring drives in Windows 2000), and it's MUCH cheaper than SCSI RAID. Your choice will depend on how you weigh cost against disk performance--and whether you really need the extra speed.
This was first published in December 2001