DUMP(8)                   BSD System Manager's Manual                  DUMP(8)

     dump - ext2 filesystem backup

     dump [-0123456789ackMnqSu] [-A file] [-B records] [-b blocksize]
          [-d density] [-e inode numbers] [-E file] [-f file] [-F script]
          [-h level] [-I nr errors] [-j compression 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.)

     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

     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
     unmounted filesystem can be used.  In the latter case, certain restric-
     tions 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
             default level is 9.

     -a      ``auto-size''.  Bypass all tape length calculations, and write
             until 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).

     -A archive_file
             Archive a dump table-of-contents in the specified archive_file to
             be used by restore(8) to determine whether a file is in the dump
             file that is being restored.

     -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
             MAXBSIZE.  The default blocksize is 10.

     -B records
             The number of 1 kB blocks per volume. Not normally required, as
             dump can detect end-of-media. When the specified size is reached,
             dump waits for you to change the volume.  This option overrides
             the calculation of tape size based on length and density.  If
             compression is on this limits the size of the compressed output
             per volume.

     -c      Change the defaults for use with a cartridge tape drive, with a
             density of 8000 bpi, and a length of 1700 feet. Specifying a car-
             tridge drive overrides the end-of-media detection.

     -d density
             Set tape density to density.  The default is 1600BPI. Specifying
             a tape density overrides the end-of-media detection.

     -e inodes
             Exclude inodes from the dump. The inodes parameter is a comma
             separated list of inode numbers (you can use stat to find the
             inode number for a file or directory).

     -E file
             Read list of inodes to be excluded from the dump from the text
             file file.  The file file should be an ordinary file containing
             inode numbers separated by newlines.

     -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
             ordinary 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 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.

     -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.

     -I nr errors
             By default, dump will ignore the first 32 read errors on the file
             system before asking for operator intervention. You can change
             this using this flag to any value. This is useful when running
             dump on an active filesystem where read errors simply indicate an
             inconsistency between the mapping and dumping passes.

     -j compression level
             Compress every block to be written on the tape using bzlib
             library. This option will work only when dumping to a file or
             pipe or, when dumping to a tape drive, if the tape drive is capa-
             ble of writing variable length blocks. You will need at least the
             0.4b24 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 compres-
             sion level bzlib will use. The default compression level is 2. If
             the optional parameter is specified, there should be no white
             space between the option letter and the parameter.

     -k      Use Kerberos authentication to talk to remote tape servers.
             (Only available if this option was enabled when dump was com-

     -L label
             The user-supplied text string label is placed into the dump
             header, 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      If this flag is specified, dump will optimise the output for
             inodes having been changed but not modified since the last dump
             ('changed' and 'modified' have the meaning defined in stat(2)).
             For those inodes, dump will save only the metadata, instead of
             saving the entire inode contents. Inodes which are either direc-
             tories or have been modified since the last dump are saved in a
             regular way.  Uses of this flag must be consistent, meaning that
             either every dump in an incremental dump set have the flag, or no
             one has it.

             Tapes written using such 'metadata only' inodes will not be com-
             patible with the BSD tape format or older versions of restore.

     -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      Make dump abort immediately whenever operator attention is
             required, without prompting in case of write errors, tape changes

     -Q file
             Enable the Quick File Access support. Tape positions for each
             inode 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
             hours when restoring single files from large backups, saves the
             tapes and the drive's head.

             It is recommended to set up the st driver to return logical tape
             positions rather than physical before calling dump/restore with
             parameter Q.  Since not all tape devices support physical tape
             positions those tape devices return an error during dump/restore
             when the st driver is set to the default physical setting.
             Please see the st man page, option MTSETDRVBUFFER, or the mt man
             page, on how to set the driver to return logical tape positions.

             Before calling restore with parameter Q, always make sure the st
             driver is set to return the same type of tape position used dur-
             ing the call to dump. Otherwise restore may be confused.

             This option can be used when dumping to local tapes (see above)
             or to local files.

     -s feet
             Attempt to calculate the amount of tape needed at a particular
             density.  If this amount is exceeded, dump prompts for a new
             tape.  It is recommended to be a bit conservative on this option.
             The default tape length is 2300 feet. Specifying the tape size
             overrides end-of-media detection.

     -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 for-
             mat of date is the same as that of ctime(3).  This option is use-
             ful for automated dump scripts that wish to dump over a specific
             period of time.  The -T option is mutually exclusive from the -u

     -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
             library. This option will work only when dumping to a file or
             pipe or, when dumping to a tape drive, if the tape drive is capa-
             ble 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 compres-
             sion level zlib will use. The default compression level is 2. If
             the optional parameter is specified, there should be no white
             space between the option letter and the parameter.

     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 nr errors).  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.

     Dump 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.  The output is verbose, so that others know that the terminal
     controlling dump is busy, 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:

           o   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

           o   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.

     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.

     /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

     fstab(5), restore(8), rmt(8)

     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.

     It might be considered a bug that this version of dump can only handle
     ext2 filesystems.  Specifically, it does not work with FAT filesystems.

     Fewer than 32 read errors (change this with -I) on the filesystem are
     ignored. If noticing read errors is important, the output from dump can
     be parsed to look for lines that contain the text 'read error'.

     Each reel requires a new process, so parent processes for reels already
     written just hang around until the entire tape is written.

     The estimated number of tapes is not correct if compression is on.

     It would be nice if dump knew about the dump sequence, kept track of the
     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.

     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

     The dump/restore backup suite is available from

     A dump command appeared in Version 6 AT&T UNIX.

dump 0.4b28                     April 12, 2002                     dump 0.4b28