The Debate Continues: One Big Hard Disk or Several Small Ones

While a big single hard disk is usually the winner from a price standpoint, having more than one disk has some significant advantages in terms of performance and safety.

Because disk capacities have increased so rapidly, there is seldom a need to put more than one disk in a system just to get enough storage. As a result, most computers come with a single disk, although they have interfaces to support two or more disks.

In general, you can expect to pay between 30 and 50 percent more for two disks than you would for a single disk of the same total capacity. This is why most people get the largest single disk they can afford.

This might be good economics, but it's not so good from a performance standpoint. With two or more disks, you have options you don't have with a single disk.

One of the major advantages of multiple disks is the ability to do striping, a storage technique that spreads data across two or more disks. Since the computer can read more than one disk at a time, this considerably speeds up data access. Striping your data across two disks will not double your read performance, but increase it by more than 50 percent.

With two disks you can do effective mirroring by putting copies of vital partitions on the other disk. This is no substitute for backup, but if a problem occurs, you can often have the all those programs and data available almost instantly.

Fortunately, this isn't a decision you have to make when you purchase your computer. With programs like Acronis True Image it is easy to add disks, create partitions, and move data from your original disk to a new one.