dump [-0123456789ackMnSu] [-B records] [-b blocksize] [-d density] [-e
inode number] [-f file] [-F script] [-h level] [-L label] [-Q file]
[-s feet] [-T date] [-z compression level] files-to-dump
dump [-W | -w]
(The 4.3BSD option syntax is implemented for backward compatibility but
is not documented here.)
DESCRIPTION
Dump examines files on an ext2 filesystem 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 -f option below for doing remote
backups). A dump that is larger than the output medium is broken into
multiple volumes. 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 specifying cartridge media, or via the tape size,
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.
files-to-dump is either a mountpoint of a filesystem or a list of files
and directories to be backed up as a subset of a filesystem. In the for
mer case, either the path to a mounted filesystem or the device of an un
mounted filesystem can be used. In the latter case, certain restrictions
are placed on the backup: -u is not allowed, the only dump level that is
supported is -0 and all the files and directories must reside on the same
filesystem.
The following options are supported by dump:
-0-9 Dump levels. A level 0, full backup, guarantees the entire file
system is copied (but see also the -h option below). A level
number above 0, incremental backup, tells dump to copy all files
new or modified since the last dump of a lower level. The de
fault level is 9.
-B records
The number of 1 kB blocks per volume. This option overrides the
end-of-media detection, and calculation of tape size based on
length and density.
-a ``auto-size''. Bypass all tape length calculations, and write un
til an end-of-media indication is returned. This works best for
most modern tape drives, and is the default. Use of this option
is particularly recommended when appending to an existing tape,
or using a tape drive with hardware compression (where you can
never be sure about the compression ratio).
-b blocksize
The number of kilobytes per dump record. Since the IO system
slices all requests into chunks of MAXBSIZE (typically 64kB), it
is not possible to use a larger blocksize without having problems
later with restore(8). Therefore dump will constrain writes to
number for a file or directory).
-h level
Honor the user ``nodump'' flag only for dumps at or above the
given level. The default honor level is 1, so that incremental
backups omit such files but full backups retain them.
-d density
Set tape density to density. The default is 1600BPI. Specifying a
tape density overrides the end-of-media detection.
-f file
Write the backup to file; file may be a special device file like
/dev/st0 (a tape drive), /dev/rsd1c (a floppy disk drive), an or
dinary file, or `-' (the standard output). 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 for
media changes. If the name of the file is of the form
``host:file'' or ``user@host:file'' dump writes to the named file
on the remote host using rmt(8). The default path name of the
remote rmt(8) program is /etc/rmt; this can be overridden by the
environment variable RMT.
-F script
Run script at the end of each tape. The device name and the cur
rent volume number are passed on the command line. The script
must return 0 if dump should continue without asking the user to
change the tape, 1 if dump dump should continue but ask the user
to change the tape. Any other exit code will cause dump to
abort. For security reasons, dump reverts back to the real user
ID and the real group ID before running the script.
-k Use Kerberos authentication to talk to remote tape servers. (On
ly available if this option was enabled when dump was compiled.)
-L label
The user-supplied text string label is placed into the dump head
er, where tools like restore(8) and file(1) can access it. Note
that this label is limited to be at most LBLSIZE (currently 16)
characters, which must include the terminating `\0'.
-M Enable the multi-volume feature. The name specified with -f is
treated as a prefix and dump writes in sequence to <prefix>001,
<prefix>002 etc. This can be useful when dumping to files on an
ext2 partition, in order to bypass the 2GB file size limitation.
-n Whenever dump requires operator attention, notify all operators
in the group ``operator'' by means similar to a wall(1).
-Q file
Enable the Quick File Access support. Tape positions for each in
ode are stored into the file file which is used by restore (if
called with parameter Q and the filename) to directly position
the tape at the file restore is currently working on. This saves
-S Size estimate. Determine the amount of space that is needed to
perform the dump without actually doing it, and display the esti
mated number of bytes it will take. This is useful with incremen
tal dumps to determine how many volumes of media will be needed.
-T date
Use the specified date as the starting time for the dump instead
of the time determined from looking in /etc/dumpdates. The format
of date is the same as that of ctime(3). This option is useful
for automated dump scripts that wish to dump over a specific pe
riod of time. The -T option is mutually exclusive from the -u
option.
-u Update the file /etc/dumpdates after a successful dump. The for
mat of /etc/dumpdates is readable by people, consisting of one
free format record per line: filesystem name, increment level and
ctime(3) format dump date. There may be only one entry per
filesystem at each level. The file /etc/dumpdates may be edited
to change any of the fields, if necessary.
-W Dump tells the operator what file systems need to be dumped.
This information is gleaned from the files /etc/dumpdates and
/etc/fstab. The -W option causes dump to print out, for all file
systems in /etc/dumpdates, and regognized file systems in
/etc/fstab. the most recent dump date and level, and highlights
those that should be dumped. If the -W option is set, all other
options are ignored, and dump exits immediately.
-w Is like -W, but prints only recognized filesystems in /etc/fstab
which need to be dumped.
-z compression level
Compress every block to be written on the tape using zlib li
brary. This option will work only when dumping to a file or pipe
or, when dumping to a tape drive, if the tape drive is capable of
writing variable length blocks. You will need at least the 0.4b22
version of restore in order to extract compressed tapes. Tapes
written using compression will not be compatible with the BSD
tape format. The (optional) parameter specifies the compression
level zlib will use. The default compression level is 2.
Dump requires operator intervention on these conditions: end of tape, end
of dump, tape write error, tape open error or disk read error (if there
is more than a threshold of 32). In addition to alerting all operators
implied by the -n key, dump interacts with the operator on dump's control
terminal at times when dump can no longer proceed, or if something is
grossly wrong. All questions dump poses must be answered by typing
``yes'' or ``no'', appropriately.
Since making a dump involves a lot of time and effort for full dumps,
dump checkpoints itself at the start of each tape volume. If writing
that volume fails for some reason, dump will, with operator permission,
restart itself from the checkpoint after the old tape has been rewound
and removed, and a new tape has been mounted.
· Always start with a level 0 backup, for example:
/sbin/dump -0u -f /dev/st0 /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:
3 2 5 4 7 6 9 8 9 9 ...
For the daily dumps, it should be possible to use a fixed num
ber 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.
ENVIRONMENT
TAPE If no -f option was specified, dump will use the device spec
ified via TAPE as the dump device. TAPE may be of the form
"tapename", "host:tapename", or "user@host:tapename".
RMT The environment variable RMT will be used to determine the
pathname of the remote rmt(8) program.
RSH Dump uses the contents of this variable to determine the name
of the remote shell command to use when doing remote backups
(rsh, ssh etc.). If this variable is not set, rcmd(3) will
be used, but only root will be able to do remote backups.
FILES
/dev/st0 default tape unit to dump to
/etc/dumpdates dump date records
/etc/fstab dump table: file systems and frequency
/etc/group to find group operator
SEE ALSO
fstab(5), restore(8), rmt(8)
DIAGNOSTICS
Many, and verbose.
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.
BUGS
It might be considered a bug that this version of dump can only handle
ext2 filesystems. Specifically, it does not work with FAT filesystems.
tapes scribbled on, told the operator which tape to mount when, and pro
vided more assistance for the operator running restore.
Dump cannot do remote backups without being run as root, due to its secu
rity history. Presently, it works if you set it setuid (like it used to
be), but this might constitute a security risk. Note that you can set RSH
to use a remote shell program instead.
AUTHOR
The dump/restore backup suite was ported to Linux's Second Extended File
System by Remy Card <card@Linux.EU.Org>. He maintained the initial ver
sions of dump (up and including 0.4b4, released in january 1997).
Starting with 0.4b5, the new maintainer is Stelian Pop
<pop@noos.fr>.
AVAILABILITY
The dump/restore backup suite is available from
http://dump.sourceforge.net
HISTORY
A dump command appeared in Version 6 AT&T UNIX.
dump 0.4b22 May 12, 2001 5
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