dump [-0123456789cnua] [-B records] [-b blocksize] [-d density] [-f file]
          [-h level] [-s feet] [-T date] filesystem
     dump [-W | -w]

     (The 4.3BSD option syntax is implemented for backward compatibility, but
     is not documented here.)

DESCRIPTION

     Dump examines files on a filesystem and determines which files need to be
     backed up. These files are copied to the given disk, tape or other stor-
     age 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.  This can be enforced by using
     the a option.

     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 op-
     tions below.  By default, the same output file name is used for each vol-
     ume after prompting the operator to change media.

     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 the same or lower level.
             The default level is 9.

     -a      ``auto-size''. Bypass all tape length considerations, and enforce
             writing until an end-of-media indication is returned.  This fits
             best for most modern tape drives.  Use of this option is particu-
             larly 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).  based on length and density.

     -B records
             The number of kilobytes per volume, rounded down to a multiple of
             the blocksize.  This option overrides the calculation of tape
             size

     -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.

     -c      Change the defaults for use with a cartridge tape drive, with a
             density of 8000 bpi, and a length of 1700 feet.


     -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.

     -n      Whenever dump requires operator attention, notify all operators
             in the group ``operator'' by means similar to a wall(1).

     -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.

     -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 flag is mutually exclusive from the -u
             flag.

     -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 flag causes dump to print out, for each file
             system in /etc/dumpdates the most recent dump date and level, and
             highlights those file systems that should be dumped.  If the -W
             flag is set, all other options are ignored, and dump exits imme-
             diately.

     -w      Is like W, but prints only those filesystems which need to be
             dumped.

     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
     are more than a threshold of 32).  In addition to alerting all operators
     implied by the -n flag, dump interacts with the operator on dump's con-
     trol 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,
           o   Always start with a level 0 backup, for example:

                     /sbin/dump -0u -f /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.

           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.

FILES

     /dev/rmt8       default tape unit to dump to
     /dev/rst*       Raw SCSI tape interface
     /etc/dumpdates  dump date records
     /etc/fstab      dump table: file systems and frequency
     /etc/group      to find group operator

SEE ALSO

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

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

     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 is written.

     Dump with the -W or -w flags does not report filesystems that have never
     been recorded in /etc/dumpdates, even if listed in /etc/fstab.

     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.