BACKUP(ADM)              XENIX System V               BACKUP(ADM)



     Name
          backup, dump - Performs incremental file system backup.

     Syntax
          backup [ key [ arguments ] filesystem ]

     Description
          backup copies all files changed after a certain date in the
          filesystem.  dump is a link to backup; they refer to the
          same utility.  The key specifies the date and other options
          about the backup, where a key consists of characters from
          the set 0123456789kfusd. The meanings of these characters
          are described below:

          f    Places the backup on file specified by the next
               argument instead of the default device.

          u    If the backup completes successfully, writes the date
               of the beginning of the backup to the file /etc/ddate.
               This file records a separate date for each file system
               and each backup level.

          0-9  This number is the ``backup level''.  Backs up all
               files modified since the last date stored in the file
               /etc/ddate for the same file system at lesser levels.
               If no date is determined by the level, the beginning of
               time is assumed; thus the option 0 causes the entire
               file system to be backed up.

          s    This is the size of the tape in feet.  The number of
               feet is taken from the next argument.  When the
               specified size is reached, backup will wait for reels
               to be changed.  The default size is 2,300 feet.

          d    This is 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.

          k    The size (in K-bytes) of the volume being written is
               taken from the next argument. If the k argument is
               specified, any s and d arguments are ignored.  The
               default is to use s and d.

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

          The first backup should be a full level-0 backup:

               backup 0u

          Next, periodic level 9 backups should be made on an



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          exponential progression of tapes or floppies:

               backup 9u

          This progression is shown as follows:

               1 2 1 3 1 2 1 4 ...

          where backup 1 is used every other time, backup 2 every
          fourth, backup 3 every eighth, etc.)  When the level-9
          incremental backup becomes unmanageable because a tape is
          full or too many floppies are required, a level-1 backup
          should be made:

               backup 1u

          After this, the exponential series should progress as if
          uninterrupted.  These level-9 backups are based on the
          level-1 backup, which is based on the level-0 full backup.
          This progression of levels of backups can be carried as far
          as desired.

          The default file system and the backup device depend on the
          settings of the variables DISK and TAPE, respectively, in
          the file /etc/default/backup.

     Files
          /etc/ddate          Records backup dates of file
                              system/level

          /etc/default/backup Default backup information

     See Also
          XENIX System Administrator's Guide
          cpio(C), default(F), dumpdir(ADM), restore(ADM), sddate(C),
          backup(F)

     Diagnostics
          If the backup requires more than one volume (where a volume
          is likely to be a floppy disk or tape), you will be asked to
          change volumes.  Press RETURN after changing volumes.














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     Notes
          Sizes are based on 1600 BPI for blocked tape.  Although the
          s and d options are used by default, they are not commonly
          used; the k option is more popular because it specifies size
          in K-bytes.  Write errors to the backup device are usually
          fatal.  Read errors on the file system are ignored.

          If the default archive medium specified in
          /etc/default/backup or /etc/default/restor is block
          structured, (example: floppy disk) then the volume size in
          Kbytes must be specified on the command line.  Neither
          utility works correctly without this information. For
          example, using the default device (below) with the backup
          command, enter the following:

               backup k 360

          The default device entry for /etc/default/backup
          (tape=/dev/xxx) and /etc/default/restor (archive=/dev/xxx)
          is /dev/rfd02.

          It is not possible to successfully restore an entire active
          root file system.

     Warning
          When backing up to floppy disks, be sure to have enough
          formatted floppies ready before starting a backup.  You must
          also be sure to close the floppy door when inserting floppy
          disks.  If you fail to do so in a multi-floppy backup, the
          entire backup will fail and you will have to begin again.

          You should never backup more than one filesystem to the tape
          devices /dev/nrct0 and /dev/nrct2.  This is because,
          although backup can write more than one filesystem to
          /dev/nrct0 or /dev/nrct2, restore may not be able to restore
          more than one filesystem from these devices.



















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