Solid-state storage may be sexy, but if you’re looking for huge capacity and tiny prices, then the classic hard disk remains unbeaten. Available capacities of portable drives with laptop-style disks inside now extends up to a whopping 2000GB, more commonly referred to as 2 terabytes (TB). Most portable USB drives are powered from the connected computer, so you can use them on the move without the need to plug into the mains.
Best portable hard drives: Capacity
Even the smallest portable hard drive you’ll likely find today will be 500GB in size, which is enough space to hold around 2000 CD albums in decent lossless FLAC format, or twice that number in lower quality MP3 or AAC format. Off-loading your music collection alone from a computer to a portable drive can be a godsend in freeing valuable space if your laptop has limited SSD storage, for example.
Another popular application of a portable hard drive is for keeping critical backups of your data held on a PC or laptop. You may be able to keep a perfect clone of your entire computer’s internal drive, on standby and ready in the event that the computer is lost or its drive should malfunction. Alternatively, you may choose just to back up the most important files and documents from your user libraries, such as text documents, photos, films, music and stored email. Some portable drives include software that can help automate this process, keeping your selected directories in sync whenever you plug in the drive or by a daily schedule.
Best portable hard drives: Performance
Now that USB 2.0 has been banished from all self-respecting storage, we find USB 3.0 as the standard for connection, letting these portable drives perform as quickly as the little disks inside will allow.
This means that when transferring your music or video collection to or from your PC, you can expect around 100MB/s read speed (and typically the same for writing, since unlike flash storage technology the read and write speeds tend to be more symmetrical). Compare this with the older drives using USB 2.0, which would limit speeds to around 35MB/s, or only one-third the speed. So in real terms, your 100GB of media files would take close to an hour to transfer with USB 2.0, or under 20 minutes using USB 3.0.
If you’re likely to be storing or backing up many small files, be aware that overall performance will plummet since hard disks tend to choke on smaller files. So while large files may zip across at 100MB/s, the smallest will likely travel at less than 1MB/s, or one hundredth that speed.
Best portable hard drives: Protection
A rugged exterior will be handy if you want the freedom of being able to throw around the unplugged drive with less worry that it will damage the unit; and more importantly lose your data.
Look out for shock-resistance ratings such as the US military MIL-STD-810F 516.5 (Transit Drop Test). This means that it should withstand being dropped 26 times onto a hard floor, once on to each face, edge and corner, from a height of 1.22m.
The drive does not need to be switched on to pass - we don’t believe any hard disk would survive that test – and nor does it require independent verification before a manufacturer can promote its product as ‘milspec shock-resistant’. But the rating is an indication that the manufacturer has probably taken more care in nurturing the delicate disk inside.
Best portable hard drives: Extras
Besides the drive itself, you can expect to find more extras included with the product. A slip-on case or even just a simple cloth pouch can prove invaluable, letting you store the drive in the bottom of a laptop or handbag without it collecting scratches and dents - or in the case of metal-cased storage drives, of leaving scratches and dents on everything around it.
At least one USB cable will be included, and you may find additional Y-cables that allow you to piggyback more power from a neighbouring USB port. This is mandatory for some portable drives, which demand more power than a single USB port can provide, for example.
Best portable hard drives: Value
For many users, a portable storage drive may be an unavoidable commodity, and price will be the deciding factor. We give a value rating based on how much each gigabyte of storage is costing you for each drive. Particularly with the largest 2TB drive, you can expect to find storage for under 5p per gigabyte now.
Best portable hard drives: Security
The larger the drive, the more you can store - and the more you stand to lose in the event of losing the drive or having it stolen. This is where it pays to lock down that drive.
There are two ways to ensure the data is unreadable by other users. You can scramble the contents through hardware encryption. Or you can use a software application to encrypt either parts or all of the drive.
The hardware-encryption option is good for defeating keyloggers and other malware already installed on your PC, and this solution also tends to be platform agnostic, so works as well with Windows, Linux or Mac computers. The disadvantage is that the security is hard-coded into the drive, so that in the event of a vulnerability being discovered there’s little chance of upgrading or fixing it.
Software encryption can be more flexible, but ensure that it works on your chosen computer platform. Ideally the software should be open-source to reduce the chance of it being compromised by deliberate back doors introduced by the developer. Unfortunately since the demise of TrueCrypt there is no cross-platform data encryption software that fits this requirement.