External Hard Drive Review

Backup storage options

The high-capacity external hard drives covered in this report are primarily intended for backup. They can also provide long-term external storage for multimedia files, such as digital video, high-resolution photos or music collections that occupy considerable hard-drive space on a computer. Although you'll sacrifice performance with most external hard drives, they can provide a convenient way to increase your storage space with the added benefit that the drive may be unplugged and connected to another computer.

We found the most comprehensive and thorough review sources to be TomsHardware.com and England's Register Hardware. Both are prolific reviewers of external hard drives, but each has different strengths: Register Hardware is objective, and TomsHardware.com compares related products in roundup reviews and shows the most comparisons in benchmark tests. XbitLabs.com is as good at testing hard drives, but experts there don't provide any at-a-glance ratings to make comparisons easy. Major computer publications such as Macworld, Laptop Magazine, PC World and PCMag.com regularly rate the best external hard drives, and ConsumerReports.org recently tested a few. Owner reviews reveal how external hard drives work in backup after backup, month after month; Amazon.com sells hundreds of hard drives and attracts hundreds of reviews, but owners who buy at Newegg.com are sometimes more knowledgeable because this site caters to computer enthusiasts and hobbyists.

External hard drives have tons of storage capacity and modest per-gigabyte (GB) costs. Other external storage options include USB flash drives, which are faster and the most portable, but capacity is currently capped at 256 GB. Furthermore, the cost per gigabyte is higher (prohibitively so for the largest 256 GB drives) and security is lower. See our companion report on USB flash drives if one or several flash drives will be enough for your storage needs. High-capacity solid state drives -- which are fast and relatively free from mechanical failure -- cost too much per gigabyte to be affordable for most people, but experts predict prices will fall in the coming year.

Measured data transfer speed is almost always the major factor in reviewer ratings. It is a big deal if you will actively use the drive, but it might not matter at all if the drive is just for backups. Reviewers also consider methods of connectivity (USB, FireWire, eSATA), ease of use, bundled or pre-installed software and physical design features, such as whether the drive sits vertically or horizontally (or can be used in either position).

Reviewers say that backup software makes a difference in the utility of these drives. Nearly all moderately priced to expensive external hard drives come with software to help schedule backups and move files, and features include system rollback capability as well as security options that keep your drive safe from sudden disconnects, shutdowns and virus invasions (a risk for drives that are switched among multiple computers). You don't need to use the manufacturer-supplied software with an external hard drive. You can drag and drop files, bypassing software entirely, or use third-party software. Budget hard drives rarely include backup software, but they are also rarely reviewed.

For the most part, the reviews we found say that the majority of external hard drives do exactly what they are supposed to do. Professional reviews are almost uniformly good across the board. However, user reviews occasionally tell another story. Newegg.com, Amazon.com and CNET's user reviews all have entries from frustrated owners who recount their hard-drive disasters.

Experts at TomsHardware.com state unequivocally that all hard drives will eventually fail, whether it's an internal or external hard drive. If you are storing crucial, irreplaceable data on an external hard drive, experts recommend creating two backups. Storing identical data on two different drives virtually eliminates the chance that you could lose all your data following a drive failure. You can use internal or external drives in a RAID array to create redundant backups, or you can use any combination of backup methods. Storing a few DVDs away from your computer can preserve your most valuable work if your computer equipment is stolen or destroyed by fire.

Just as the hard drive inside your computer could falter at virtually any point, the same goes for an external hard drive. An external hard drive should most definitely be part of a larger backup and storage plan -- not your only repository for important, irreplaceable data files, photos, video or other information.

According to reviews, some hard drives are quiet in operation, but others generate noise that can be as annoying as a commercial jingle you can't clear from your head. Heat and reliability are closely related, and any electronic product that runs too hot can be a failure waiting to happen. Several factors can be used to gauge reliability; those include brand history and reputation, user reviews, the manufacturer's limited warranty for a specific drive and the manufacturer's mean time between failures (MTBF) specification (not all manufacturers publish one).

MTBF It tells you how long (in hours) an average unit will last. A 2007 Carnegie Mellon University study found that MTBF estimates are grossly exaggerated. The worst drives failed 15 times sooner than projected. Therefore, you can't trust an individual MTBF figure, but the differences in MTBF figures can be meaningful. Experts still recommend redundant backups of key data.