A common model creates /, /home and /var
partitions as discussed above. This is simple to install and
maintain and differentiates well enough to avoid adverse
effects from different lifetimes. It fits well into a backup
model, too: Almost noone bothers to backup USENET news spools
and only some files in /var are worth backing up
(/var/spool/mail comes to mind). On the other hand,
/ changes infrequently and can be backuped upon demand
(after configuration changes) and is small enough to fit on
most modern backup media as a full backup (plan 250 to 500 MB
depending on the amount of installed software). /home
contains valuable user data and should be backuped daily.
Some installations have very large /homes and must use
incremental backups.
Some systems put /tmp onto a seperate partition as well, others
symlink it to /var/tmp to achieve the same effect (note that
this can affect single user mode, where /var will be
unavailable and the system will have no /tmp until you create
one or mount /var manually) or put it onto a RAM disk (Solaris
does this for example). This keeps /tmp out of /, a good idea.
This model is convenient for upgrades or reinstallations as
well: Save your configuration files (or the entire /etc) to
some /home directory, scrap your /, reinstall and fetch the old
configurations from the save directory on /home.