Spotlight: Give Your Storage a Boost

• See our chart: Monster-Size Storage

Fortunately, it's a fine time to add a massive new hard drive to your system. The average price per gigabyte is at an all-time low--just under a buck for the typical Serial ATA interface model, and about 75 cents for tested models that use the earlier but still very common Parallel ATA interface. Whether you want to swap out your old drive for a new 400GB behemoth, or you're ready to make your existing drive part of a two-drive RAID configuration for better speed or for redundancy, we've found a model for you.

The PC World Test Center tested units from all five major manufacturers of hard drives: Hitachi, Maxtor, Samsung, Seagate, and Western Digital. We ran seven SATA drives and six PATA drives through a suite of tests designed to compare write speeds and seek times. Then we examined each drive's retail bundle as a whole to determine which package provided the best overall value for the money.

SATA-iated

SATA hard drives arrived on the scene about two years ago, but they're becoming the mainstream drive of choice only now. The lag was not wholly unexpected: Since most motherboards supported only the Parallel ATA interface at the time SATA drives debuted, early SATA adopters had to buy PCI adapter cards. Today, however, most new motherboards offer integrated SATA connections (as well as legacy PATA connectors); and market research firm IDC expects SATA drive shipments to outstrip PATA by mid-2005.

SATA's refined design represents a step up. PATA ribbon cables are wide and impede air flow; SATA cables are easier to attach and significantly less bulky. SATA drives are simpler to connect and configure, too, with no master/slave jumpers to set. And finally, SATA offers greater bandwidth. Its maximum transfer rate of 150 megabytes per second is an improvement on PATA's maximum rate of 133 MBps. The transfer-rate headroom may not translate into extraordinary performance gains in single-drive systems, but it can pay off nicely in multidrive and RAID setups in which several drives access the data bus simultaneously.

After SATA

Drive vendors are already looking beyond the original SATA specification. The next evolution of SATA doubles SATA's peak transfer rate to 300 MBps. Another new feature is native command queuing (NCQ), which enables a drive to store and execute commands independently in the most efficient order possible. Of the 13 drives we tested, only the models from Maxtor and Seagate support NCQ.

Whether you're upgrading your hard drive or buying one for a system you're building from scratch, you'll need to make a number of decisions. First, decide which interface you want. If you have an older PATA system, you might still consider buying a SATA drive, along with an inexpensive SATA interface card (but make sure that you have an available PCI slot). In our Test Center appraisals, SATA drives did better than their PATA rivals. On average, the SATA group copied files and folders in 17 percent less time than the PATA drives, and copied a single 3GB file in 20 percent less time. You may not see the same gains with a different configuration or an older PC, but the improved cabling can still help your system's airflow. And it will be easier to transfer the drive you get today to the next PC you buy.

Other buying criteria include capacity, price, rotational speed, and buffer size. Capacity needs are very user-dependent; but graphics, music, and video mavens should go for the biggest size they can afford, since media files eat up hard-drive real estate in a hurry. At current prices, 250GB drives are the most economical--about 68 cents per gigabyte. But newer, 400GB drives are priced just 7 cents higher per gigabyte, making them suitable as a hedge against future storage needs.

The great majority of mainstream hard drives spin their platters at 7200 rpm. You should avoid the increasingly rare 5400-rpm drives if performance is a primary consideration. Only one manufacturer--Western Digital--today makes a 10,000-rpm ATA drive. The company's 74GB Raptor WD740GD uses the SATA interface; it was designed for use in enterprise RAID configurations. It's no slouch in a desktop RAID 0 setup, either: When we paired Raptors in a RAID configuration, we got outstanding performance (see "Hard Drives Gain Racing Stripes")--even though the Raptor lagged slightly behind the average SATA drive in some of our single-drive tests. Because of its relatively small capacity and high performance in arrays, the Raptor is often configured in RAID arrangements in high-end desktops and servers. Gamers and video editors, in particular, can benefit from this type of setup.

Though buffer size is a basic drive spec, assessing the merits of different buffer sizes is difficult. The PC World Test Center's evaluation of these drives didn't reveal any direct correlation between buffer size and improved speed: In both the PATA and the SATA categories, the fastest drives used 8MB buffers, while several runners-up employed 16MB buffers.