Hard disks:
Hard drives usually consist of several disks on a single spindle. Each disk surface is able to store data and this has its own advantage that each surface can have its own read/write head as shown in figure 4.4. This enables the read/write heads to operate simultaneously, which means that the data can be transferred more quickly than by using a single larger disk. Hard disks are available in all sorts of sizes and bigger sizes are becoming available all the time. A typical personal computer will have a hard disk capacity of around 10 GB (10000 MB).
Magnetic tapes:
Large spools of tape are used by very large computer systems that need to hold huge amounts of data. They are not as common as they use to be. Tapes in cartridges are now becoming more popular. These look similar to audio cassettes, except that they are larger. Their main use is for making backup (security) copies of hard disks.
…
