hard drive: interfaces

HARD DRIVES: INTERFACES. Getting the best from your hard drive is not all about spindle speed and maximum capacity. These are obviously important, but the type of connection the hard drive has to the rest of your system is equally critical. The two main types of connection are SCSI (Small Computer System Interface) and UDMA (Ultra Direct Memory Access). A SCSI interface has a maximum data transfer rate of 160 MBps (Megabytes Per Second). Standard UDMA has a transfer rate of 100 MBps, so SCSI provides more bandwidth. Another advantage of SCSI is that it lets you daisy-chain as many as 15 devices, whereas UDMA can only connect two per channel. So why doesn’t everyone opt for SCSI? Part of the reason is that it is expensive, but another factor is that it isn’t integrated on most motherboards. If you want SCSI you need to buy a SCSI you need to buy a SCSI card because most motherboards don’t have built-in support for it. You’ll need a hard drive that supports SCSI, too. These options are much more expensive than UDMA. Nearly all new PCs have UDMA cable as standard and you find it isn’t worth the extra expensive and difficulty of SCSI simply to boost data transfer rates by 60MBps.