Today, hard drives are measured in hundreds of gigabytes. Soon it may be terabytes, and we'll look back on the gigabyte wondering how we ever got along with so little storage. We're really halfway there already. Hitachi's Deskstar 7K500, currently the largest desktop hard drive on the market, offers an awe-inspiring half-terabyte of storage. 500GB in a 3.5" form factor that was bursting at the seams with just 20MB so many years ago.

Storage would be pretty stagnant if additional gigabytes were all new hard drives had to offer, but there's more to the Deskstar 7K500 than its copious capacity. The drive also comes equipped with a generous 16MB cache, as well as support for 300MB/s Serial ATA transfer rates and Native Command Queuing—all the bells and whistles you'd expect from a high-end drive. But does it have enough punch to keep up with the latest from Maxtor, Seagate, and Western Digital? Read on to find out.

Drive specs
The 7K500 is just one of whole wave of new Deskstars to support 300MB/s Serial ATA transfer rates and Native Command Queuing (NCQ). Here's how the drive's specs compare with the Deskstar T7K250, which we reviewed back in May.

Despite its industry-leading 500GB capacity, the 7K500 packs only 100GB per platter. Hitachi uses denser 125GB platters in the T7K250, and those platters would presumably allow the 7K500 to be built with four rather than five disks. Denser platters could also improve the drive's performance by allowing the drive head to access more data from the same physical area.

Despite its lower areal density, the 7K500's claimed internal and sustained transfer rates are only marginally slower than those of the T7K250. Areal density can only do so much, and both drives do spin at 7,200 RPM. They also share identical average seek times and rotational latencies.

The 7K500 and T7K250 differ when it comes to cache size, though. Hitachi's 500GB monster packs an impressive 16MB of cache—double that of the T7K250. 16MB of cache is quickly becoming standard for high-end Serial ATA drives, with the latest drives from Maxtor and Western Digital also making the jump from 8MB. More cache is better, of course, but since manufacturers tune caching algorithms differently, not all 16MB caches will have the same performance characteristics.

As it is with cache, more is also better when it comes to warranties. After a brief flirtation with single-year coverage, hard drive manufacturers are moving back to three-year warranties, and we couldn't be happier. Well, maybe we could. While the Deskstar 7K500's three-year warranty is much better than an insulting one-year warranty, it would be nice if Hitachi and other manufacturers matched Seagate's five-year hard drive warranties—not that longer warranties guarantee lower failure rates, just more replacement coverage.