xrestore(ADM)                   19 June 1992                   xrestore(ADM)


 Name

    xrestore, xrestor - invoke XENIX incremental filesystem restorer

 Syntax

    xrestore key [ arguments ]

    xrestor key [ arguments ]

 Description

    The xrestore command is used to read archive media backed up with the
    xbackup(ADM) command.

    The key specifies what is to be done.  key is one of the characters cC,
    rR, tT, or xX optionally combined with k and/or f or F.  xrestor is an
    alternate spelling for the same command.

    c,C   Verify (check) a dump tape.  Used after a dump is made to make sure
          the tape has no I/O errors or bad checksums.  C is the same as c
          except that it provides a higher level of checking.

    f     Uses the first argument as the name of the archive (backup device
          /dev/*) instead of the default.

    F     F is the number of the first file on the tape to read.  All files
          up to that point are skipped.

    k     Follow this option with the size of the backup volume.  This allows
          for reading multi-volume dumps from media such as floppies.

    r,R   The archive is read and loaded into the file system specified in
          argument.  This should not be done without proper consideration
          (see below).  If the key is R, xrestore asks which archive of a
          multi-volume set to start on.  This allows xrestore to be inter-
          rupted and then restarted (an fsck must be done before the res-
          tart).

    t     Prints the date the archive was written and the date the file sys-
          tem was backed up.

    T     Prints a full listing of a dump tape.  Similar to t.

    x     Each file on the archive named by an argument is extracted.  The
          filename has all ``mount'' prefixes removed; for example, if /usr
          is a mounted file system, /usr/bin/lpr is named /bin/lpr on the
          archive.

          The extracted file is placed in a file with a numeric name supplied
          by xrestore (actually the inode number).  In order to keep the
          amount of archive read to a minimum, the following procedure is
          recommended:

          1.  Mount volume 1 of the set of backup archives.

          2.  Type the xrestore command with the appropriate key and argu-
              ments.

          3.  xrestore will check xdumpdir, then announce whether or not it
              found the files, give the numeric name that it will assign to
              the file, and in the case of a tape, rewind to the start of the
              archive.

          4.  It then asks you to ``mount the desired tape volume''.  Type
              the number of the volume you choose.  On a multi-volume backup,
              the recommended procedure is to mount the last through the
              first volumes, in that order.  xrestore checks to see if any of
              the requested files are on the mounted archive (or a later
              archive, thus the reverse order). If the requested files are
              not there, xrestore doesn't read through the tape.  If you are
              working with a single-volume backup or if the number of files
              being xrestored is large, respond to the query with 1 and xre-
              store will read the archives in sequential order.

    X     Same as x except that files are replaced in original location.
          When you use this option, omit the initial slash ( / ) in the
          filename on the xrestore command line.

    The r option should only be used to xrestore a complete backup archive
    onto a clear file system, or to xrestore an incremental backup archive
    onto a file system so created.  It should not be used to xrestore a
    backup archive onto the root file system.  Thus:

       /etc/mkfs /dev/hd1 10000
       xrestore r /dev/hd1

    is a typical sequence to xrestore a complete backup.  Another xrestore
    can be done to get an incremental backup in on top of this.

    A xbackup followed by a mkfs and an xrestore is used to change the size
    of a file system.

 Files

    rst*                   Temporary files
    /etc/default/restor    Name of default archive device

    The default archive unit varies with installation.

 Notes

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

    Note also that xrestore may be unable to xrestore more than one file-
    system from the tape devices /dev/nrct0 and /dev/nrct2.

 Diagnostics

    There are various diagnostics involved with reading the archive and writ-
    ing the disk.  There are also diagnostics if the i-list or the free list
    of the file system is not large enough to hold the dump.

    If the dump extends over more than one disk or tape, xrestore may ask you
    to change disks or tapes.  Reply with a newline when the next unit has
    been mounted.

 See also

    fsck(ADM), mkfs(ADM), sddate(C), xbackup(ADM), xdumpdir(ADM)

 Value added

    xrestor and xrestore are extensions of AT&T System V developed by The
    Santa Cruz Operation, Inc.