dump(8) and restore(8) are the
traditional Unix backup programs. They operate on the drive as a
collection of disk blocks, below the abstractions of files, links
and directories that are created by the filesystems.
dump(8) backs up devices, entire filesystems, not parts
of a filesystem and not directory trees that span more than one
filesystem, using either soft links ln(1) or mounting
one filesystem onto another. dump(8) does not write
files and directories to tape, but rather writes the data blocks
that are the building blocks of files and directories.
dump(8) has quirks that remain from its early days in
Version 6 of ATT Unix (circa 1975). The default parameters are
suitable for 9-track tapes (6250 bpi), not the high-density media
available today (up to 62,182 ftpi). These defaults must be
overridden on the command line to utilize the capacity of current
tape drives.
rdump(8) and rrestore(8) backup data
across the network to a tape drive attached to another computer.
Both programs rely upon rcmd(3) and ruserok(3)
to access the remote tape drive. Therefore, the user performing
the backup must have rhosts access to the remote
computer. The arguments to rdump(8) and
rrestore(8) must suitable to use on the remote computer.
(e.g. When rdump'ing from a FreeBSD computer to an
Exabyte tape drive connected to a Sun called komodo, use: /sbin/rdump
0dsbfu 54000 13000 126 komodo:/dev/nrst8 /dev/rsd0a 2>&1)
Beware: there are security implications to allowing
rhosts commands. Evaluate your situation carefully.