Although tape has traditionally been the
media of choice, new forms of backup media are starting to become
popular including optical CD Recordable (CD-R) disks, and CD
Re-writable (CD-RW) optical disks. Various forms of magnetic media
such as removable hard drives,. Jaz™, and Zip™ disks are also
becoming more common. Most of these backup media are not intended to
back up large volumes of data, but they are a flexible alternative that
is very fast and can be treated as another disk drive on the computer.
Disk drives, whether magnetic or optical, have one characteristic in
common: they are random access devices. Instead of advancing or
rewinding, as with tape, they can seek and find the desired file in a
fraction of a second. This makes them very flexible for backing up
relatively small amounts of data (usually less than one or two
Gigabytes). There are writable CD changers that can handle very large
amounts of data with maximum flexibility; however, they are relatively
expensive. Figure
shows the variety of backup media
available and Figure
lists them in order of capacity.
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