6. Magnetic Tape

The amount of work that you do on your computer at home can easily be backed up onto a CD-RW or a memory stick. However, many organisations, such as your school or an office, need to back up large volumes of data each day. A CD-RW, DVD-RW or flash memory sticks just would not be large enough for doing this.

Large organisations who need to back up their systems daily tend to use magnetic tapes to store their data.

Magnetic tape uses 'serial access' to find a piece of data.

To find a specific piece of data, you have to start at the beginning of the tape and continue fast forwarding until you get to the piece of data that you need. This makes it fairly slow to find and retrieve data so it would not be much use to store data that you needed to get hold of quickly.

Magnetic tape has the advantage over large external hard disks - they are much cheaper and so are very popular as an archive medium.

Advantages

• Relatively cheap per megabyte of storage
• Can store large amounts of data - over 100 Gb
• Can be set up to do the back up overnight or over the weekend
• Robotic archive and backup systems can swap tapes in and out automatically

Disadvantages

• Serial access so can be quite slow to access data
• Need a special piece of equipment to record and read the data on the tape
• Less robust than other media as the tape can easily break