.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
-.\" $Id: dump.8.in,v 1.58 2005/06/01 13:44:35 stelian Exp $
+.\" $Id: dump.8.in,v 1.61 2009/06/18 09:36:52 stelian Exp $
.\"
.TH DUMP 8 "version __VERSION__ of __DATE__" BSD "System management commands"
.SH NAME
.B dump:
.TP
.BI \-level#
-The dump level (any integer). A level 0, full backup, guarantees the
-entire file system is copied (but see also the
+The dump level (any integer). A level 0, full backup, specified by
+.B \-0
+guarantees the entire file system is copied (but see also the
.B \-h
option below). A level number above 0, incremental backup, tells
.B dump
to
copy all files new or modified since the last dump of a lower level. The
-default level is 9. Historically only levels 0 to 9 were usable in
+default level is 0. Historically only levels 0 to 9 were usable in
dump, this version is able to understand any integer as a dump level.
.TP
.BI \-a
This should be done at set intervals, say once a month or once every two months,
and on a set of fresh tapes that is saved forever.
.IP \(em
-After a level 0, dumps of active file systems are taken on a daily basis, using
-a modified Tower of Hanoi algorithm, with this sequence of dump levels:
+After a level 0, dumps of active file systems are taken on a daily basis,
+with this sequence of dump levels:
.RS 14
.B 3 2 5 4 7 6 9 8 9 9 ...
.RE
After several months or so, the daily and weekly tapes should get rotated out
of the dump cycle and fresh tapes brought in.
.PP
+Another backup strategy is the Tower of Hanoi sequence, which reuses
+older tapes in a way that for newer dates the available restore points
+are more frequent, then for older dates (see
+http://en.wikipedia.org/wiki/Backup_rotation_scheme for additional
+information).
+.PP
(The 4.3BSD option syntax is implemented for backward compatibility but is not
documented here.)
.SH ENVIRONMENT