Partitioning is a means to divide a single hard drive into many
logical drives. A partition is a contiguous set of blocks on a drive
that are treated as an independant disk. A partition table (the
creation of which is the topic of this HOWTO) is
an index that relates sections of the hard drive to partitions.
Why have multiple partitions?
Encapsulate your data. Since file system corruption is local to a
partition, you stand to lose only some of your data if an accident occurs.
Increase disk space efficiency. You can format partitions with
varying block sizes, depending on your usage. If your data is in a
large number of small files (less than 1k) and your partition uses 4k
sized blocks, you are wasting 3k for every file. In general, you waste
on average one half of a block for every file, so matching block size
to the average size of your files is important if you have many files.
Limit data growth. Runaway processes or maniacal users can consume
so much disk space that the operating system no longer has room on the
hard drive for its bookkeeping operations. This will lead to
disaster. By segregating space, you ensure that things other than the
operating system die when allocated disk space is exhausted.
Partitions must not overlap. This will cause data corruption
and other spooky stuff.
There ought to be be no gap between adjacent partitions. While
this is not harmful, you are wasting precious disk space by
leaving space between partitions.
A disk need not be partitioned completely. You may decide to
leave some unpartitioned space at the end of your disk and
partition it later.
Partitions cannot be moved but they can be resized and copied
using special software. This HOWTO only
covers the use of the fdisk utility, which does not
permit any of these operations.