(tar) Multi-Volume Archives

Info Catalog

(tar) Using Multiple Tapes

(tar) Tape Files

 
 Archives Longer than One Tape or Disk
 -------------------------------------
 
      _(This message will disappear, once this node revised.)_
 
    To create an archive that is larger than will fit on a single unit of
 the media, use the `--multi-volume' (`-M') option in conjunction with
 the `--create' (`-c') option ( create).  A "multi-volume"
 archive can be manipulated like any other archive (provided the
 `--multi-volume' (`-M') option is specified), but is stored on more
 than one tape or disk.
 
    When you specify `--multi-volume' (`-M'), `tar' does not report an
 error when it comes to the end of an archive volume (when reading), or
 the end of the media (when writing).  Instead, it prompts you to load a
 new storage volume.  If the archive is on a magnetic tape, you should
 change tapes when you see the prompt; if the archive is on a floppy
 disk, you should change disks; etc.
 
    You can read each individual volume of a multi-volume archive as if
 it were an archive by itself.  For example, to list the contents of one
 volume, use `--list' (`-t'), without `--multi-volume' (`-M') specified.
 To extract an archive member from one volume (assuming it is described
 that volume), use `--extract' (`--get', `-x'), again without
 `--multi-volume' (`-M').
 
    If an archive member is split across volumes (ie. its entry begins on
 one volume of the media and ends on another), you need to specify
 `--multi-volume' (`-M') to extract it successfully.  In this case, you
 should load the volume where the archive member starts, and use `tar
 --extract --multi-volume'--`tar' will prompt for later volumes as it
 needs them.   extracting archives, for more information about
 extracting archives.
 
    `--info-script=SCRIPT-NAME' (`--new-volume-script=SCRIPT-NAME', `-F
 SCRIPT-NAME') is like `--multi-volume' (`-M'), except that `tar' does
 not prompt you directly to change media volumes when a volume is
 full--instead, `tar' runs commands you have stored in SCRIPT-NAME.  For
 example, this option can be used to eject cassettes, or to broadcast
 messages such as `Someone please come change my tape' when performing
 unattended backups.  When SCRIPT-NAME is done, `tar' will assume that
 the media has been changed.
 
    Multi-volume archives can be modified like any other archive.  To add
 files to a multi-volume archive, you need to only mount the last volume
 of the archive media (and new volumes, if needed).  For all other
 operations, you need to use the entire archive.
 
    If a multi-volume archive was labeled using `--label=ARCHIVE-LABEL'
 (`-V ARCHIVE-LABEL') ( label) when it was created, `tar' will not
 automatically label volumes which are added later.  To label subsequent
 volumes, specify `--label=ARCHIVE-LABEL' (`-V ARCHIVE-LABEL') again in
 conjunction with the `--append' (`-r'), `--update' (`-u') or
 `--concatenate' (`--catenate', `-A') operation.
 
 `--multi-volume'
 `-M'
      Creates a multi-volume archive, when used in conjunction with
      `--create' (`-c').  To perform any other operation on a
      multi-volume archive, specify `--multi-volume' (`-M') in
      conjunction with that operation.
 
 `--info-script=PROGRAM-FILE'
 `-F PROGRAM-FILE'
      Creates a multi-volume archive via a script.  Used in conjunction
      with `--create' (`-c').
 
    Beware that there is _no_ real standard about the proper way, for a
 `tar' archive, to span volume boundaries.  If you have a multi-volume
 created by some vendor's `tar', there is almost no chance you could
 read all the volumes with GNU `tar'.  The converse is also true: you
 may not expect multi-volume archives created by GNU `tar' to be fully
 recovered by vendor's `tar'.  Since there is little chance that, in
 mixed system configurations, some vendor's `tar' will work on another
 vendor's machine, and there is a great chance that GNU `tar' will work
 on most of them, your best bet is to install GNU `tar' on all machines
 between which you know exchange of files is possible.
 

Info Catalog

(tar) Using Multiple Tapes

(tar) Tape Files