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     DUMP(1M)                                                 DUMP(1M)

          dump - incremental file system dump

          dump [ key [ argument ... ] filesystem ]

          Dump copies to magnetic tape all files changed after a cer-
          tain date in the filesystem. The key specifies the date and
          other options about the dump.  Key consists of characters
          from the set 0123456789fusd.

          f    Place the dump on the next argument file instead of the

          u    If the dump completes successfully, write the date of
               the beginning of the dump on file `/etc/ddate'.  This
               file records a separate date for each filesystem and
               each dump level.

          0-9  This number is the `dump level'.  All files modified
               since the last date stored in the file `/etc/ddate' for
               the same filesystem at lesser levels will be dumped.
               If no date is determined by the level, the beginning of
               time is assumed; thus the option 0 causes the entire
               filesystem to be dumped.

          s    The size of the dump tape is specified in feet.  The
               number of feet is taken from the next argument. When
               the specified size is reached, the dump will wait for
               reels to be changed.  The default size is 2300 feet.

          d    The density of the tape, expressed in BPI, is taken
               from the next argument. This is used in calculating the
               amount of tape used per write. The default is 1600.

          If no arguments are given, the key is assumed to be 9u and a
          default file system is dumped to the default tape.

          Now a short suggestion on how perform dumps.  Start with a
          full level 0 dump

               dump 0u

          Next, periodic level 9 dumps should be made on an exponen-
          tial progression of tapes.  (Sometimes called Tower of Hanoi
          - 1 2 1 3 1 2 1 4 ...  tape 1 used every other time, tape 2
          used every fourth, tape 3 used every eighth, etc.)

               dump 9u

     DUMP(1M)                                                 DUMP(1M)

          When the level 9 incremental approaches a full tape (about
          78000 blocks at 1600 BPI blocked 20), a level 1 dump should
          be made.

               dump 1u

          After this, the exponential series should progress as unin-
          terrupted.  These level 9 dumps are based on the level 1
          dump which is based on the level 0 full dump.  This progres-
          sion of levels of dump can be carried as far as desired.

          default filesystem and tape vary with installation.
          /etc/ddate: record dump dates of filesystem/level.

          restor(1), dump(5), dumpdir(1)

          If the dump requires more than one tape, it will ask you to
          change tapes.  Reply with a new-line when this has been

          Sizes are based on 1600 BPI blocked tape.  The raw magtape
          device has to be used to approach these densities.  Read
          errors on the filesystem are ignored.  Write errors on the
          magtape are usually fatal.