A common model creates
/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 backup up on 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 up 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