...Then my backup fails or worse the disk is completely full because writing to /dev/nst0 when the device file doesn't exist creates a data file on the disk which grows to be bigger than the /dev partition.
That's a bug in the backup application. Group "disk" is sufficient to do a backup (that's why the group exists). If the backup utility doesn't work from raw partitions and thus needs root to read from the filesystem then it should be dropping privs before writing to /dev/st (otherwise it's going to ignore the permission bits). That's not a bug that mattered overly much until dynamic device names. But almost all Unixen have that now so the program needs fixing. -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
