I sometimes feel that the computer industry is trying to destroy SCSI, or at the least, lock the low and midrange market out of it completely. I know this sounds harsh, but just look at the evidence:

  • SCSI devices usually cost much more than equivalent devices with a different interface. Look at SCSI Scanners vs. USB Scanners, SCSI hard disks vs. IDE hard disks, and so on. With hard disks, the price difference can be vast; a modern 18GB SCSI drive costs the same as a modern 60GB IDE drive.
  • It is difficult to find devices with a SCSI interface in mass market computer stores. If the mass market isn't allowed to adopt it, the prices will never go down.
  • Apple Computer has abolished on-board SCSI in their machines recently. Apple was once the primary supporter of SCSI in the consumer market, but they recently defected to IDE and USB as well.
  • The IDE bus is just now starting to perform as well as Ultra2 SCSI did a few years ago. The industry could have adopted SCSI instead of continuing to improve IDE, which was poorly designed from the start.

SCSI is a very powerful interface. Its high cost is entirely artificial; the computer industry is trying to keep it out of the hands of regular consumers so that it can continue to milk the high end. This is another example of better technology giving way to an inferior solution.

SCSI is not intended to be the mass-consumer storage medium. It's made more for commercial enterprises. SCSI drives last far longer than IDE drives. That's why high-end servers use SCSI and RAID-SCSI devices for mission-critical systems.

Apple is abandoning SCSI for FireWire on the high end and USB on the low end, and many of their machines have IDE for internal drives. All of these technologies are smaller and cheaper than on board SCSI. Sun is still using Ultra Wide SCSI in some of its servers, but is using IDE in its low end workstations, and Fibre channel on its very high end systems.

Apple does support scsi still, but in the form of a firewire to scsi adapter (very expensive, oops), or a PCI SCSI add on card. This is (obviously) only available in the tower systems with PCI slots.

The biggest problem with SCSI is that it requires proper termination, and even some hardware vendors can't get this right. IDE doesn't need termination (as much), because the bus length is shorter and there are fewer drives on the bus. USB and Firewire are prefered over scsi probably due to simpler bus connection, smaller cables, and hot plug capability, which is more appropriate for portable zip drives, scanners, cameras, etc. Meanwhile, much of the functionality of scsi has been subsumed into IDE.

SCSI has a much higher per-command overhead, which is balanced out with its superior ability to issue multiple simultaneous commands, which explains one of the reasons why scsi usually outperforms IDE in multiuser conditions, even when their bandwidths are similar. Firewire is fast, and beats older scsi, but newer scsi still is faster with its multiwire parallel bus.

SCSI is a good alternative when you need more than IDE or firewire can give, but still can't afford fibre channel.

Log in or registerto write something here or to contact authors.