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The old sideshow barker's patter about "amazing, colossal, and stupendous" attractions could well apply to the latest crop of hard disk drives. In our last roundup of drives, in October 1999, 20GB models were among the biggest. Now 20GB drives are middle-of-the-road and often appear in low-cost PCs.

This time around, we review what Ed Sullivan might have called " really big" drives. Yes, if your data-storage needs and your budget are modest, a good selection of drives is available in the vicinity of 20GB. At the other extreme, some drives hover in the 60GB-to-80GB range. But the sweet spot where you get ample capacity for a reasonable price now lies around 40GB.

We tested ten flagship drives from four major manufacturers: IBM, Maxtor, Seagate, and Western Digital. We evaluated IBM's 20.5GB Deskstar 40GV, as well as the company's 46.1GB and 75.1GB Deskstar 75GXP models. Maxtor provided the 40.9GB DiamondMax VL 40, the 60.5GB DiamondMax Plus 60, and the 81GB DiamondMax 80. Seagate sent two 40GB drives--the U Series 5 and the Barracuda ATA III. And finally, Western Digital supplied the 20GB WD Protégé and the 40GB WD Caviar.

Quantum, the other big name in consumer hard drives, is missing from our list because its new drive, the Fireball Plus AS, was not ready in time for this article. But you can read our review, " New Quantum Fireball: Gobs of Gigs." While working on our review, we also learned that Maxtor has purchased Quantum's hard drive operations. The two companies are working out a merger, but for now, each maintains its own line of drives. Other manufacturers, including Fujitsu, Hitachi, Samsung, and Toshiba, are omitted because they primarily sell bare drives to original equipment manufacturers such as PC vendors, not directly to consumers.

Squeezing In Data

In most cases, today's drives offer twice the capacity of last year's models for about the same price. On a per-gigabyte basis, prices for this year's crop range from $3.83 to $7.06, with half the drives falling in the range from $4 to $5. If you're looking to make a modest investment, a 20GB drive is a great choice--with an average street price of just over $100; 40GB drives, depending on rotational speed, run from $145 to $195. If you want the maximum storage space, you'll need to lay down a few more bucks: Figure on spending about $300 to $500 for drives with capacities between 60GB and 80GB.

You can get more storage for the same price every time you upgrade, thanks to the continuing increase in areal density--the amount of data that can be stored on a single, two-sided disk platter. To make an even bigger drive, manufacturers stack up multiple platters. Most vendors stop at four platters per drive, but IBM manages to squeeze a fifth platter into a standard 1-inch-high case.

A couple of years ago, a platter could store only 5GB of data. That figure jumped to 10GB around January 2000, and 20GB platters were becoming standard by the fall of last year. (All the drives here pack approximately 20GB per platter, with the exception of IBM's 15GB-per-platter Deskstar 75GXP drives.) At press time, we learned that Western Digital had upped the areal density in its new WD Caviar drive to 30GB per platter.

Greater areal density allows manufacturers to reduce the number of components in drives of a given capacity, which lowers their cost. Packing data closer together also speeds up performance, since read/write heads don't have to travel as far to find information. A year ago, a 20GB hard drive had to consist of two platters and two pairs of read/write heads (one head for each side of a platter). But 20GB drives using today's technology have just one platter and a single pair of heads.

Some industry analysts expect areal density to reach 40GB per platter toward the end of this summer. If that happens, we could see drives with capacities of 200GB by the end of the year. Those same pundits expect areal density to double again, to 80GB per platter, sometime in 2002. But hard drive makers say that 80GB per platter is close to the current limit, and that squeezing any more data onto one disk will require the integration of new and more-expensive technologies.

Delivering Data Faster

Beyond the push to expand storage capacity, there's a genuine need to deliver the data faster, triggered by gigahertz-plus CPUs and data-hungry operations such as video processing.

Several factors determine how quickly a drive can read or write data. One is rotational speed: Five of the drives we review spin their disks at 5400 revolutions per minute, the remaining five at 7200 rpm. A faster rotational speed lets the read/write heads cover more of the disk and read or write more data in the same amount of time. The 7200-rpm drives we looked at usually outperformed the 5400-rpm units, but not always. In our time tests, the fastest 5400-rpm drives, like Maxtor's DiamondMax 80 and DiamondMax VL 40, outran the slower 7200-rpm models, such as Seagate's Barracuda ATA III.

In addition to increasing the rotational speed, manufacturers can squeeze out better performance by fine-tuning the design of read/write heads and the algorithms that control them. It seems more than coincidental that the fastest 5400-rpm drives here come from the same vendor that produced the top-performing 7200-rpm model.

Performance also varies with the size of a hard drive's internal cache--memory used to store recently accessed data temporarily and to front-load adjacent data that an application may request next. In all cases, drives with a 2048KB cache outperformed those with only a 512KB cache.

Then there is the matter of how quickly a drive communicates with the rest of the system. Most PCs sitting on desks today use the Ultra DMA/66 (also known as Ultra ATA/66) flavor of the IDE interface, which can deliver data in bursts of up to 66MB per second. (In regular use, drives transfer data at well below the burst rate.)

The newest PCs generally use the Ultra DMA/100 interface, with a maximum burst rate of 100 MBps. Industry analysts expect Ultra DMA/100 to remain the standard interface until the end of this year. Early in 2002, though, the next interface, Ultra DMA/133, is slated to appear.

All the drives reviewed here use Ultra DMA/100, and we tested them on a PC equipped with a matching interface, courtesy of an Ultra DMA/100 add-in card from Promise Technologies. We then retested the fastest 7200-rpm and 5400-rpm drives with a Promise Ultra DMA/66 card.

Our informal tests of maximum burst rate showed that the drives performed a bit slower with the Ultra DMA/66 interface, but we found no significant difference in the PC World Test Center's real-world, application-based performance tests. That's not surprising. For years, the capacity of the Ultra DMA interface has outpaced the sustained transfer rate of a single hard drive. But the excess capacity present in the interface will be available to accommodate faster drives later on.

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