Installation guide

If the partition is not available, these commands return an error message
and ask if you want to continue, as shown in the following example:
# newfs /dev/rrz8c
WARNING: disklabel reports that rz8c currently
is being used as "4.2BSD" data. Do you want to
continue with the operation and possibly destroy
existing data? (y/n) [n]
Applications, as well as operating system commands, can modify the
fstype of the disk label, to indicate that a partition is in use. See the
check_usage
(3) and set_usage(3) reference pages for more information.
7–32 Administering the UNIX File System