The performance hit caused by misaligned partitions is real: After we corrected a misaligned partition on one of the 3TB drives we tested, it improved its performance by nearly 30 percent on writing groups of small files and folders.

Utilities available from hard-drive vendors and from third parties such as Paragon Software will align existing partitions, but doing so can be a very slow process. Realigning my mostly full 1TB data drive with Paragon's Alignment Tool took upwards of 10 hours.

The big three drive manufacturers--Hitachi, Seagate, and Western Digital--each sent us a for testing. All three drives were very good performers when writing and reading large files, as well as when reading small files and folders. Two of them, the Hitachi Deskstar 7K3000 and Seagate Barracuda XT, did well in writing large amounts of small files, too, while the Western Digital Caviar Green (the drive that had the aforementioned alignment issue) struggled slightly in this scenario. Overall, the Deskstar 7K3000 was the best performer, albeit by only about 10 percent over the Seagate Barracuda XT. The WD Caviar Green lagged a little behind, but keep in mind that the Green is oriented toward conserving power. It varies its rotational speed between writes, which hurts it when copying lots of smaller files--one part of our testing. (Click the chart below to view it at full size.)

Another differentiator between the drives turned out to be the software. Hitachi includes a driver/partitioning utility (from Paragon Software) that allows you to utilize all 3TB in a single partition. By contrast, as of this writing, the Acronis software favored by Seagate and WD allows you to use the entire drive capacity, but only in separate 2.2TB and 800GB partitions. To create a single volume, you need to follow the previously mentioned tip about combining partitions using Windows dynamic disks.