Tape technology has continued to evolve but is less likely to be used in a modern system. Modern backup systems tend to use off site combined with local removable disk drive technologies. Still, FreeBSD will support any tape drive that uses SCSI, such as LTO and older devices such as DAT. There is limited support for SATA and USB tape drives.
FreeBSD uses the sa(4) driver, providing
/dev/sa0
,
/dev/nsa0
, and
/dev/esa0
. In normal use, only
/dev/sa0
is needed.
/dev/nsa0
is the same physical drive
as /dev/sa0
but does not rewind the
tape after writing a file. This allows writing more than one
file to a tape. Using /dev/esa0
ejects the tape after the device is closed, if
applicable.
mt(1) is the FreeBSD utility for controlling other operations of the tape drive, such as seeking through files on a tape or writing tape control marks to the tape.
For example, the first three files on a tape can be preserved by skipping past them before writing a new file:
#
mt -f /dev/nsa0 fsf 3
An example of writing a single file to tape using tar(1):
#
tar cvf /dev/sa0 file
Recovering files from a tar(1) archive on tape into the current directory:
#
tar xvf /dev/sa0
A simple backup of /usr
with dump(8):
#
dump -0aL -b64 -f /dev/nsa0 /usr
Interactively restoring files from a dump(8) file on tape into the current directory:
#
restore -i -f /dev/nsa0
Higher-level programs are available to simplify tape backup. The most popular are Amanda and Bacula. These programs aim to make backups easier and more convenient, or to automate complex backups of multiple machines. The Ports Collection contains both these and other tape utility applications.
All FreeBSD documents are available for download at http://ftp.FreeBSD.org/pub/FreeBSD/doc/
Questions that are not answered by the
documentation may be
sent to <freebsd-questions@FreeBSD.org>.
Send questions about this document to <freebsd-doc@FreeBSD.org>.