External Hard Disk Drives

With everyone using computers nowadays, external hard drives are an important part of any gadget arsenal. They're great for backing up important information as well as archiving old photos, videos, and music. These gadgets also make bringing around large files possible.

Capacity

The most important capability for any external hard drive is how much data it can store, or its capacity. Capacities are represented by gigabyte (abbreviated as GB) and terabyte (TB) values. In practical terms, a gigabyte can store two movies, two-hundred songs, a thousand medium-sized pictures or over fifteen-thousand documents.

With music collections, movies, and even office documents taking up gigabytes of space, a decent capacity nowadays ranges from 500GB to 1TB. Any external hard drive that stores less will be filled up in no time, while higher-capacity drives may be too expensive.

When a new external hard drive is plugged into a computer, its available space will always be significantly lower than the capacity as claimed by the manufacturer. This is because for computers, a gigabyte is the space taken up by exactly 1,073,741,824 letters (or bytes). Those who produce hard disks and other kinds of storage devices for computers define a gigabyte as 1 billion characters—a discrepancy of about 73 million. Many external hard drives also come with software preinstalled, which take up some space.

Connectivity

Most external hard drives connect to a computer through a USB or Firewire port, though the first kind is the most popular used nowadays. Firewire connections have always allowed faster file transfers between the computer and the hard drive, but the latest version of USB (USB 3.0) eliminates this lead. More manufacturers also support the technology, so if you're looking for a future-proofed external hard drive, you should get one that supports USB 3.0.

Hard Disk Form Factor

All external hard drives contain at least one hard disk. Some manufacturers list a form factor with the drive's specs, which indicates the size of the hard disk inside. Two common types are the 3.5” and 2.5” form factors.

3.5” hard disks are larger, meaning the external hard drives using them will be bigger in size. They're the same type used in most desktop computers. They require more power to operate, which is why all external hard drives based on this form factor require an external power source—they usually have to be plugged into a computer and wall socket.

2.5” hard disks are the same kind used in most laptops, and they don't need as much power. Their smaller size enables their use in more compact external hard drives, which can draw all the power they need from the computer.

Hard drives using 3.5” disks are usually designed to stay beside the computer most of the time. They also provide more capacity per dollar spent, and as a general rule transfer files to and from the PC faster, because the hard disk itself reads and writes data faster. There are 2.5” external drives that match the storage space of their 3.5” counterparts, but do so at a higher price. The flipside is that many of them are small enough to fit in your pocket.

Functions

Many external hard drives act as extra disks that provide additional storage for the computer they're plugged into. Yet there are also more advanced options on the market that offer more advanced features, such as media playback and network storage.

Media playback and network storage drives act like normal drives when plugged into computers. But they can also connect to TVs and play any movies and music on the disk. Network storage drives on the other hand can plug into a router, so that everyone connected to the same network (like a WiFi hotspot) can access the files stored.

It goes without saying that as you select external hard drives with more features, you can expect to pay more the added functionality. The same is true when buying external hard drives that contain several hard disks inside.