Maneuvering the Disk Drive Alphabet SoupSo you're going to build a new system and you're looking at storage devices. What's the difference between IDE, ATA, SATA and SCSI disk drives? What kind do you want in your system? The alphabet soup all refers to disk drive interfaces, the way a disk or other peripheral connects to the rest of your computer. The major differences are performance and price. Generally, the more expensive a disk drive interface is the higher the performance you can expect. The least expensive, slowest, and by far the most common interface is IDE, also known as Parallel ATA or EIDE in its more recent incarnations. Both the cheapest computers and the cheapest disk drives are designed for Parallel ATA. Don't be dissuaded, Parallel ATA, or simply ATA drives, are the heart and soul of the consumer computer market and a huge part of the business desktop market. How much of a problem ATA/IDE's lack of speed depends in large part on what you are doing. A computer is no faster than its slowest subsystem and the speed of the disk interface often isn't always the bottleneck. For most home and office use, Web surfing, and such, the disk drive isn't likely to be a major problem. For this reason, we can expect that IDE/ATA will stick around for some time to come. ATA/IDE comes in two flavors. The regular 100 MHz IDE and 133 MHz Ultra ATA, which is about a third faster and otherwise similar. SATA stands for Serial ATA. It is a faster, more modern version of IDE/ATA and is becoming more widely available. It offers better performance at a cost about 20 to 30 percent higher than IDE/ATA equipment. The maximum data transfer rate of a SATA interface is 150 MB/sec. compared to less than 50 MB/sec of IDE/ATA drives. SATA has some additional advantages, because it is a serial (bit-at-a-time) interface, it doesn't need the bulky flat ribbon cables that clutter up the innards for IDE/ATA machines. A thinner cable also is better for air flow within the computer, allowing system fans to be more efficient and thereby keep the computer cooler. Remember, heat is the enemy of all electronic things. SATA is becoming popular in everything from home computers to big corporations. Big companies like it because it offers a much cheaper alternative to SCSI at a price not much higher than IDE/ATA. Home users like SATA because it gives considerable performance boost for not a lot more money. There are also predictions that in a few years SATA will challenge SCSI for the high-performance throne. SCSI (Small Computer System Interface) is the Cadillac of drive interfaces, lots of performance in a highly standard package at a premium price. It offers more sheer speed than the other disk interfaces. Like IDE, SCSI has been around for a number of years and has gone through a number of versions, each faster than the previous. Currently most SCSI users are buying Ultra 320 devices, which have a data transfer rate of 320 MB/sec. That performance comes at a price, both in cost and complexity. While many motherboards have IDE/ATA interfaces and more and more are sporting SATA interfaces, SCSI is almost always supplied on a separate card. SCSI devices also need to be properly terminated (because you can daisychain quite a few SCSI devices, you need a special connector on the last device to "terminate" the chain) and have a few other quirks that you need to learn to install them properly. The big issue is money. While an 80 Gb IDE drive would usually sell for less than $80, an 80 Gb SCSI drive is likely to be upwards of $500. This isn't just because of the interface. SCSI drives are traditionally built to higher standards with longer expected life spans than IDE drives. Because SCSI drives are usually used in disk arrays, they come in smaller capacities than IDE or SATA drives. There is still a good market for 18 Gb SCSI drives, for example, while it's hard to find an IDE drive much under 30 Gb. High-end game machines, servers, and similar computers often use SCSI interfaces. In general, a system that has to move a lot of data into and out of storage is a likely candidate for the SCSI interface.
| 
Acronis Inc. Backup software.