Labs

External Hard Disks

Several factors determine how quickly a hard disk can copy files. Cache memory, interface, spindle speed and data density all play a part. This makes it difficult to guess the speed of a disk from its specification.

To test how quickly each hard disk can read and write files, we use an automated benchmarking script. Files are copied from a PC's RAM to the hard disk and back again. We use the PC's RAM as the source of the file transfer as it's much faster than any hard disk and ensures that we get the fastest possible performance from each disk.

In the first test we copy a 100MB file to and from the disk 100 times. This shows how it copes with large files such as videos and images. Next, we copy some small files totalling 100MB to and from each disk. This shows how quickly small files, such as system files, are copied during a system backup.

If a disk has more than one interface, we repeat all our tests for each one.