The external hard drives covered in this report can be used to store copies of important data or to provide long-term external storage for multimedia files, such as digital video, high-resolution photos or music collections that can 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 can be unplugged and connected to another computer.
Different external hard drives excel at different tasks. Some can transfer giant multimedia files quickly, while others let you take your files on the go or store them on a network. Most external hard drives are still mechanical, writing to and reading from spinning platters. Hard disk drives (HDD) offer the advantage of higher storage capacity at a relatively low cost per gigabyte (GB). External solid state drives (SSD) that use flash memory in the place of spinning disks are becoming more available, however.
Costs are at a point where they can be a consideration. SSDs are much faster than traditional HDDs and are more reliable because they don't include moving parts -- such as rapidly spinning disks. However, capacities are still capped, and recovering data from an SSD that has failed is nearly impossible, while recovering data from a failed disk drive might be possible, albeit expensive.
Some external hard drives are portable, while others are meant to be parked on a desk. Desktop external drives are faster, in general, than their portable counterparts, and they are available in larger capacities, so they are the best choice for those who need to store scads of large video and other multimedia files. Portable external hard drives are smaller and lighter, and they don't need an external power source to operate -- drawing power instead from the computer to which they are connected. They make it easy to take your data and files with you for use on any computer.
Reviewers say that backup software can make a difference in the usability of an external hard drive. Nearly all but the cheapest 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).
At the same time, most reviewers won't downrate an external hard drive too severely if its software falls short. 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. Most such software is Windows only; however, most drives that are Mac compatible work very well with Apple's Time Machine software, which is well regarded.
Aside from capacity, the key factors separating external hard drives are their transfer speed and their reliability, and those considerations along with relative value are used to name our top choices. Reviews by those with expertise in evaluating external hard drives are considered. We also place considerable weight on user reviews, as these turn up long-term issues that expert reviewers can miss.
A case in point is external hard drive reliability. The sad fact is that every mechanical HDD ever made will fail eventually, taking its data with it. The best external hard drives have long mean times between failures, but that's something that expert reviewers can rarely address because they can't spend a long enough time with an individual drive to judge its robustness. However, user reviews can provide great insight, and we rely on these extensively in our assessments of external drive reliability.