LinuxPlanet: New HOWTO: Linux Partition HOWTO

“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.”

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