Tape back-up devices are useful when it comes to storing a back up copy of a computer hard disk. They are often employed by web hosts to store customer data in the rare event of a power outage or equipment failure. The entire contents of a computer hard disk can be placed safely on a tape back-up cassette and restored onto a new machine if needed. It’s important to make the use of a tape back-up part of routine and regular maintenance so that a very recent copy of the hard disk can be recovered.
Tapes are magnetic media similar to hard disks except for how the data is stored and accessed. While a disk drive is random access, meaning parts of a file may be stored in several non-sequential places, data on a magnetic tape is sequentially stored. This is not a problem because the hardware and software used to connect and access the data handles the difference on the fly.
Most tape back-ups are done nightly using magnetic tape cartridges that are of a greater capacity than the hard drives they are backing up. Tape back-ups can be compressed in a 2:1 ratio but can also store uncompressed data as needed.