Pack rats, beware

It would be tough to argue against installing a bigger hard drive on your home computer. Who wouldn't want more room to store digital pictures and music files? But the same assumption is not true when it comes to federal agencies, where the need for cheap, voluminous storage is even greater.

It turns out that ever-roomier hard drives are not always what agencies need or even want. Regardless of a drive's storage capacity, there is only one way for data to get on or off it, and that's via a mechanical arm that glides just above the spinning disk's surface.

The concern is "contention," which is when a storage system has to juggle

multiple requests for data access at the same time, slowing overall throughput speeds.

"As drives get larger [capacity-wise], there is a good chance that you are storing many different types of data on one drive, increasing the potential for contention," said Alex Gorbansky, a senior analyst with Taneja Group, a storage consulting firm.

Peter Steege, global product marketing manager at hard-drive manufacturer Seagate Technology, said concerns about access speeds are what make the company's 36G and 73G drives the preferred choices among enterprise customers, even though disks that can store hundreds of gigabytes — at much lower costs per gigabyte — are readily available.

Buyers increasingly recognize that applications involving

frequent, random reads and writes, such as databases for

online transactions and some Web sites, will perform better with a greater number of fast, lower-capacity drives, Steege said.

Meanwhile, applications that focus on large, infrequently accessed files, such as digital images, work better with larger-capacity drives.