External Drive Options

 
 
By Loyd Case  |  Posted 2003-01-16 Email Print this article Print
 
 
 
 
 
 
 


Several external drive options exist at different levels of performance, capacity, and redundancy. One of the oldest types of externally attached subsystems used SCSI drives. Outboard SCSI RAID arrays are still used for certain mission-critical applications mostly in businesses. The SAN, or storage area network, offers another enterprise-class external storage solution. While personal SANs may someday make it into our homes, for now SANs are still considered high-end and beyond the scope of this piece, which focuses on personal external storage. A few external IDE storage products have also been on the market, but havent been completely satisfactory. They have been, for the most part, not hot swappable, so you typically had to power down to swap out a drive. And you were still limited by the number of free IDE ports on a system. The most common variant has been drive bays that slide into the PC case and plug into an internal connector.
IDEs short cable length (24 inches, tops) has been the major limiting factor for IDE-based external drives. However, as Serial ATA begins to take off, well see more external drives, because the maximum cable length has increased to 1 meter.
After FireWire arrived on the scene, FireWire external hard drives used as backup or secondary storage became a familiar item, especially in Macintosh shops. On the PC side, IEEE1394 was less prevalent, as the standard has only recently become popular in most PCs and motherboards. Now that PCI firewire cards cost less than $15, these offer another viable option. But USB 2.0 is a standard feature on all current generation motherboards, so it obviates the need to install a PCI card. Finally, a few external drives existed for USB 1.1 connections, but the maximum transfer rate of 12 megabits per second was too limiting for serious data transfer. Once USB 2.0 hit the streets, USB became an interesting option. Weve seen a number of external CD and DVD recordable drives support USB 2.0. We reviewed several examples of these back in August. External hard drives have been somewhat slower in coming, but now theyre arriving in force, and most of the major hard drive suppliers now sell external drives supporting either FireWire or USB 2.0 -- or both.
While buying a drive thats already integrated in an enclosure has its appeal, you can also build one yourself. That way, you can choose the capacity and performance you need. Unlike SCSI, however, external USB and FireWire drives wont match the performance of an internal drive. A SCSI drive is a SCSI drive, whether its external or internal. However ATA drives today all support high speed DMA transfers, while USB and FireWire do not. Because of this, you might conceivably see performance differences that depend on the speed of the host CPU. Since you typically wont be using an external drive as primary storage, the differences shouldnt matter. What it does mean, however, is that you can get away without using the fastest possible ATA drive. We deliberately chose a newer drive, the 7200rpm Seagate Barracuda ATA V, which we reviewed in our big drive feature. It wasnt the fastest in our roundup, but if we hit any performance limitations in USB 2.0, it should show up on this drive -- and we also get to toss in a comparison with our recent Serial ATA test. We chose to use a USB 2.0 external drive enclosure kit from Belkin.


 
 
 
 
Loyd Case came to computing by way of physical chemistry. He began modestly on a DEC PDP-11 by learning the intricacies of the TROFF text formatter while working on his master's thesis. After a brief, painful stint as an analytical chemist, he took over a laboratory network at Lockheed in the early 80's and never looked back. His first 'real' computer was an HP 1000 RTE-6/VM system.

In 1988, he figured out that building his own PC was vastly more interesting than buying off-the-shelf systems ad he ditched his aging Compaq portable. The Sony 3.5-inch floppy drive from his first homebrew rig is still running today. Since then, he's done some programming, been a systems engineer for Hewlett-Packard, worked in technical marketing in the workstation biz, and even dabbled in 3-D modeling and Web design during the Web's early years.

Loyd was also bitten by the writing bug at a very early age, and even has dim memories of reading his creative efforts to his third grade class. Later, he wrote for various user group magazines, culminating in a near-career ending incident at his employer when a humor-impaired senior manager took exception at one of his more flippant efforts. In 1994, Loyd took on the task of writing the first roundup of PC graphics cards for Computer Gaming World -- the first ever written specifically for computer gamers. A year later, Mike Weksler, then tech editor at Computer Gaming World, twisted his arm and forced him to start writing CGW's tech column. The gaming world -- and Loyd -- has never quite recovered despite repeated efforts to find a normal job. Now he's busy with the whole fatherhood thing, working hard to turn his two daughters into avid gamers. When he doesn't have his head buried inside a PC, he dabbles in downhill skiing, military history and home theater.
 
 
 
 
 
 
 

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