.\" Copyright (c) 1980, 1991 Regents of the University of California.
.\" %sccs.include.redist.man%
.\" @(#)dump.8 6.9 (Berkeley) %G%
.Op Cm 0123456789fusdWn Op Ar argument ...
and determines which files
need to be backed up. These files
are copied to the given disk, tape or other
storage medium for safe keeping (see the
option below for doing remote backups).
A dump that is larger than the output medium is broken into
On most media the size is determined by writing until an
end-of-media indication is returned.
On media that cannot reliably return an end-of-media indication
(such as some cartridge tape drives)
each volume is of a fixed size;
the actual size is determined by the tape size and density and/or
block count options below.
By default, the same output file name is used for each volume
after prompting the operator to change media.
The following options are supported by
guarantees the entire file system is copied.
copy all files new or modified since the
last dump of the same or lower level. The default
may be a special device file
Multiple file names may be given as a single argument separated by commas.
Each file will be used for one dump volume in the order listed;
if the dump requires more volumes than the number of names given,
the last file name will used for all remaining volumes after prompting
If the name of the file is of the form
writes to the named file on the remote host using
requires operator attention,
notify all operators in the group
Attempt to caluculate the amount of tape needed
If this amount is exceeded,
It is recommended to be a bit conservative on this option.
The default tape length is 2300 feet.
is readable by people, consisting of one
free format record per line:
There may be only one entry per filesystem at each level.
may be edited to change any of the fields,
tells the operator what file systems need to be dumped.
This information is gleaned from the files
to print out, for each file system in
the most recent dump date and level,
and highlights those file systems that should be dumped.
option is set, all other options are ignored, and
Is like W, but prints only those filesystems which need to be dumped.
requires operator intervention on these conditions:
disk read error (if there are more than a threshold of 32).
In addition to alerting all operators implied by the
interacts with the operator on
control terminal at times when
or if something is grossly wrong.
Since making a dump involves a lot of time and effort for full dumps,
checkpoints itself at the start of each tape volume.
If writing that volume fails for some reason,
with operator permission,
restart itself from the checkpoint
after the old tape has been rewound and removed,
and a new tape has been mounted.
tells the operator what is going on at periodic intervals,
including usually low estimates of the number of blocks to write,
the number of tapes it will take, the time to completion, and
the time to the tape change.
so that others know that the terminal
and will be for some time.
In the event of a catastrophic disk event, the time required
to restore all the necessary backup tapes or files to disk
can be kept to a minimum by staggering the incremental dumps.
An efficient method of staggering incremental dumps
to minimize the number of tapes follows:
.Bl -bullet -offset indent
Always start with a level 0 backup, for example:
.Bd -literal -offset indent
/etc/dump 0uf /dev/nrst1 /usr/src
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.
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:
.Bd -literal -offset indent
For the daily dumps, it should be possible to use a fixed number of tapes
for each day, used on a weekly basis.
Each week, a level 1 dump is taken, and
the daily Hanoi sequence repeats beginning with 3.
For weekly dumps, another fixed set of tapes per dumped file system is
used, also on a cyclical basis.
After several months or so, the daily and weekly tapes should get
rotated out of the dump cycle and fresh tapes brought in.
.Bl -tag -width /etc/dumpdates -compact
default tape unit to dump to
dump table: file systems and frequency
Dump exits with zero status on success.
Startup errors are indicated with an exit code of 1;
abnormal termination is indicated with an exit code of 3.
Fewer than 32 read errors on the filesystem are ignored.
Each reel requires a new process, so parent processes for
reels already written just hang around until the entire tape
options does not report filesystems that have never been recorded
knew about the dump sequence,
kept track of the tapes scribbled on,
told the operator which tape to mount when,
and provided more assistance
command appeared in Version 6 AT&T UNIX.
projects / unix-history / blob