External Hard Drive Features

An external hard drive provides extra memory and mobility.external hardrive image by Photoeyes from Fotolia.com

External hard drives meet two of the emerging needs of high-end computer users. First, since people are storing more and more media on their home systems, the storage capacity on existing internal hard drives may no longer be enough. Second, people who have multiple computers--at work, at home and a netbook while on the move, for example--need to have access to data in different locations. Storing data on an external hard drive accomplishes this.

Storage

The most important feature of an external hard drive is the amount of memory that it has. Desktop drives, which are designed to spend most of their time in the same place and need to be plugged in in order to work, can have as much as 4 terabytes, or 4,000 gigabytes, or more of storage capacity. As of September 2010, portable drives top out at about 1 terabyte, although half that amount is more common.

USB ports are the most common way for external hard drives to connect to a computer. USB 3.0, which is backward compatible with USB 2.0 and promises to be blazing fast, is becoming available as of September 2010, but USB 2.0 is more common. The upload and download rates for an eSATA connection are nearly 10 times faster than a USB 2.0 connection, but this option is significantly more expensive. External hard drives that use an eSATA connection must also be connected to a power source, while those that use a USB port can be powered by the computer.

Solid-state drives use transistors instead of a spinning disk, making them much faster than traditional hard drives. This makes them an excellent choice for internal hard drives, but because external hard drives are limited by the type of connection used, an SSD external hard drive only makes sense if you are using an eSATA connection. SSD drives are also more expensive than traditional hard drives.

If you need to be able to pass a few files from one computer to another, but don't need a significant amount of memory, you should consider flash memory. A memory stick with a few gigabytes of memory is cheap, reliable and can fit on a key chain, making it much more convenient than a hard drive if you just need to take a few documents home from the office.