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DUMP(8)			  System management commands		       DUMP(8)

NAME
       dump - ext2/3/4 filesystem backup

SYNOPSIS
       dump  [-level#]	[-ackMnqSuv] [-A file] [-B records] [-b blocksize] [-d
       density] [-D file] [-e inode numbers] [-E file] [-f file]  [-F  script]
       [-h  level]  [-I	 nr errors] [-jcompression level] [-L label] [-Q file]
       [-s feet] [-T date] [-y] [-zcompression level] files-to-dump

       dump [-W | -w]

DESCRIPTION
       Dump examines files on an  ext2/3/4  filesystem	and  determines	 which
       files  need  to be backed up. These files are copied to the given disk,
       tape or other storage 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.

       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 specifying cartridge media, or via the
       tape size, density and/or block count options below.  By	 default,  the
       same output file name is used for each volume after prompting the oper‐
       ator to change media.

       files-to-dump is either a mountpoint of a filesystem or a list of files
       and  directories	 to  be	 backed up as a subset of a filesystem. In the
       former case, either the path to a mounted filesystem or the  device  of
       an  unmounted  filesystem  can  be  used.  In  the latter case, certain
       restrictions are placed on the backup: -u is not allowed, the only dump
       level  that  is	supported  is 0 and all the files and directories must
       reside on the same filesystem.

OPTIONS
       The following options are supported by dump:

       -level#
	      The dump level (any integer). A level 0, full backup,  specified
	      by  -0 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 a lower level. The default level is 0. Historically
	      only  levels 0 to 9 were usable in dump, this version is able to
	      understand any integer as a dump level.

       -a     “auto-size”. Bypass all  tape  length  calculations,  and	 write
	      until  an	 end-of-media indication is returned.  This works best
	      for most modern tape drives, and is the  default.	 Use  of  this
	      option is particularly 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).

       -A archive_file
	      Archive  a  dump table-of-contents in the specified archive_file
	      to be used by restore(8) to determine whether a file is  in  the
	      dump file that is being restored.

       -b blocksize
	      The  number  of kilobytes per dump record. The default blocksize
	      is 10, unless the -d option has been used to specify a tape den‐
	      sity  of 6250BPI or more, in which case the default blocksize is
	      32. Th maximal value is 1024.  Note however that, since  the  IO
	      system slices all requests into chunks of MAXBSIZE (which can be
	      as low as 64kB), you can experience problems  with  dump(8)  and
	      restore(8)  when	using a higher value, depending on your kernel
	      and/or libC versions.

       -B records
	      The number of 1 kB blocks per volume. Not normally required,  as
	      dump  can	 detect	 end-of-media.	When  the  specified  size  is
	      reached, dump waits for you to change the volume.	  This	option
	      overrides	 the calculation of tape size based on length and den‐
	      sity. If compression is on this limits  the  size	 of  the  com‐
	      pressed  output  per  volume.  Multiple values may be given as a
	      single argument separated by commas.  Each value	will  be  used
	      for  one	dump  volume in the order listed; if dump creates more
	      volumes than the number of values given, the last value will  be
	      used  for	 the  remaining volumes. This is useful for filling up
	      already partially filled media (and then	continuing  with  full
	      size volumes on empty media) or mixing media of different sizes.

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

       -d density
	      Set tape density to density.  The default is 1600BPI. Specifying
	      a tape density overrides the end-of-media detection.

       -D file
	      Set the path name of the file storing the information about  the
	      previous	full  and  incremental	dumps. The default location is
	      /etc/dumpdates.

       -e inodes
	      Exclude inodes from the dump. The inodes parameter  is  a	 comma
	      separated list of inode numbers (you can use stat(1) to find the
	      inode number for a file or directory).

       -E file
	      Read list of inodes to be excluded from the dump from  the  text
	      file  file.  The file file should be an ordinary file containing
	      inode numbers separated by newlines.

       -f file
	      Write the backup to file; file may be a special device file like
	      /dev/st0	(a  tape  drive), /dev/rsd1c (a floppy disk drive), an
	      ordinary file, or - (the standard output). Multiple  file	 names
	      may be given as a single argument separated by commas. Each file
	      will be used for one dump volume in the  order  listed;  if  the
	      dump  requires  more volumes than the number of names given, the
	      last file name will used for all remaining volumes after prompt‐
	      ing  for	media  changes. If the name of the file is of the form
	      host:file or user@host:file dump writes to the named file on the
	      remote  host  (which should already exist, dump doesn't create a
	      new remote file) using rmt(8).  The default  path	 name  of  the
	      remote rmt(8) program is /etc/rmt; this can be overridden by the
	      environment variable RMT.

       -F script
	      Run script at the end of each tape (except for  the  last	 one).
	      The  device name and the current volume number are passed on the
	      command line. The script must return 0 if dump  should  continue
	      without  asking  the  user  to change the tape, 1 if dump should
	      continue but ask the user to change the  tape.  Any  other  exit
	      code  will  cause	 dump  to  abort.  For	security reasons, dump
	      reverts back to the real user ID and the real  group  ID	before
	      running the script.

       -h level
	      Honor  the user nodump flag UF_NODUMP only for dumps at or above
	      the given level.	The default honor level is 1, so  that	incre‐
	      mental backups omit such files but full backups retain them.

       -I nr errors
	      By  default,  dump  will	ignore the first 32 read errors on the
	      file system before asking for  operator  intervention.  You  can
	      change  this  using  this flag to any value. This is useful when
	      running dump on an active filesystem where  read	errors	simply
	      indicate	an  inconsistency  between  the	 mapping  and  dumping
	      passes.

	      A value of 0 means that all read errors will be ignored.

       -jcompression level
	      Compress every block to be  written  on  the  tape  using	 bzlib
	      library.	This  option  will work only when dumping to a file or
	      pipe or, when dumping to a tape drive,  if  the  tape  drive  is
	      capable  of  writing  variable  length  blocks. You will need at
	      least the 0.4b24 version of restore in  order  to	 extract  com‐
	      pressed  tapes. Tapes written using compression will not be com‐
	      patible with the BSD tape format. The (optional) parameter spec‐
	      ifies the compression level bzlib will use. The default compres‐
	      sion level is 2. If the optional parameter is  specified,	 there
	      should  be  no  white  space  between  the option letter and the
	      parameter.

       -k     Use Kerberos authentication to  talk  to	remote	tape  servers.
	      (Only  available	if  this option was enabled when dump was com‐
	      piled.)

       -L label
	      The user-supplied text string label  is  placed  into  the  dump
	      header,  where  tools like restore(8) and file(8) can access it.
	      Note that this label is limited to be at most LBLSIZE (currently
	      16) characters, which must include the terminating \0.

       -m     If  this	flag  is  specified, dump will optimise the output for
	      inodes having been changed but not modified since the last  dump
	      ('changed' and 'modified' have the meaning defined in stat(2) ).
	      For those inodes, dump will save only the metadata,  instead  of
	      saving  the  entire  inode  contents.   Inodes  which are either
	      directories or have been modified since the last dump are	 saved
	      in  a regular way. Uses of this flag must be consistent, meaning
	      that either every dump in an incremental dump set have the flag,
	      or no one has it.

	      If  you use this option, be aware that many programs that unpack
	      files from archives (e.g. tar, rpm, unzip, dpkg) may set	files'
	      mtimes  to  dates	 in the past.  Files installed in this way may
	      not be dumped correctly using "dump -m" if the modified mtime is
	      earlier than the previous level dump.

	      Tapes written using such 'metadata only' inodes will not be com‐
	      patible with the BSD tape format or older versions of restore.

       -M     Enable the multi-volume feature. The name specified  with	 f  is
	      treated  as a prefix and dump writes in sequence to <prefix>001,
	      <prefix>002 etc. This can be useful when dumping to files on  an
	      ext2/3/4 partition, in order to bypass the 2GB file size limita‐
	      tion.

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

       -q     Make  dump  abort	 immediately  whenever	operator  attention is
	      required, without	 prompting  in	case  of  write	 errors,  tape
	      changes etc.

       -Q file
	      Enable  the  Quick  File Access support. Tape positions for each
	      inode are stored into the file file which is used by restore (if
	      called  with parameter -Q and the filename) to directly position
	      the tape at the file restore is currently working on. This saves
	      hours  when restoring single files from large backups, saves the
	      tapes and the drive's head.

	      It is recommended to set up the st driver to return logical tape
	      positions	 rather than physical before calling dump/restore with
	      parameter -Q.  Since not all tape devices support physical  tape
	      positions those tape devices return an error during dump/restore
	      when the st driver is  set  to  the  default  physical  setting.
	      Please  see  the	st(4) man page, option MTSETDRVBUFFER , or the
	      mt(1) man page, on how to set the driver to return logical  tape
	      positions.

	      Before  calling  restore with parameter -Q, always make sure the
	      st driver is set to return the same type of tape	position  used
	      during the call to dump.	Otherwise restore may be confused.

	      This  option can be used when dumping to local tapes (see above)
	      or to local files.

       -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. Specifying the tape size
	      overrides end-of-media detection.

       -S     Size estimate. Determine the amount of space that is  needed  to
	      perform  the  dump  without  actually  doing it, and display the
	      estimated number of bytes it will	 take.	This  is  useful  with
	      incremental dumps to determine how many volumes of media will be
	      needed.

       -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)  followed	by  an
	      rfc822  timezone specification: either a plus or minus sign fol‐
	      lowed by two digits for the number of hours and two  digits  for
	      the  minutes.  For example, -0800 for eight hours west of Green‐
	      wich or +0230 for two hours and a half east of  Greenwich.  This
	      timezone	offset	takes  into  account daylight savings time (if
	      applicable to the timezone): UTC offsets when  daylight  savings
	      time  is	in effect will be different than offsets when daylight
	      savings time is not in effect. For backward compatibility, if no
	      timezone	is specified, a local time is assumed.	This option is
	      useful for automated dump scripts that wish to dump over a  spe‐
	      cific  period  of time. The -T option is mutually exclusive from
	      the -u option.

       -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	 followed by a rfc822 timezone
	      specification (see the -u option for details).  If  no  timezone
	      offset  is  specified,  times are interpreted as local. Whenever
	      the file is written, all dates in the file are converted to  the
	      local  time  zone,  without changing the UTC times. There may be
	      only one entry per filesystem at each level. The file /etc/dump‐
	      dates may be edited to change any of the fields, if necessary.

       -v     The  -v  (verbose)  makes	 dump to print extra information which
	      could be helpful in debug sessions.

       -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 option causes dump to	 print	out,  for  all
	      file  systems in /etc/dumpdates , and recognized file systems in
	      /etc/mtab and /etc/fstab.	 the most recent dump date and	level,
	      and  highlights those that should be dumped. If the -W option is
	      set, all other options are ignored, and dump exits immediately.

       -w     Is like -W, but prints only recognized filesystems in  /etc/mtab
	      and /etc/fstab which need to be dumped.

       -y     Compress	every  block  to  be written to the tape using the lzo
	      library.	This doesn't compress as well as the zlib library  but
	      it's  much faster.  This option will work only when dumping to a
	      file or pipe or, when dumping to a tape drive, if the tape drive
	      is  capable of writing variable length blocks.  You will need at
	      least the 0.4b34 version of restore in  order  to	 extract  com‐
	      pressed  tapes. Tapes written using compression will not be com‐
	      patible with the BSD tape format.

       -zcompression level
	      Compress every block to  be  written  on	the  tape  using  zlib
	      library.	This  option  will work only when dumping to a file or
	      pipe or, when dumping to a tape drive,  if  the  tape  drive  is
	      capable  of  writing  variable  length  blocks. You will need at
	      least the 0.4b22 version of restore in  order  to	 extract  com‐
	      pressed  tapes. Tapes written using compression will not be com‐
	      patible with the BSD tape format. The (optional) parameter spec‐
	      ifies  the compression level zlib will use. The default compres‐
	      sion level is 2. If the optional parameter is  specified,	 there
	      should  be  no  white  space  between  the option letter and the
	      parameter.

       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 is more than a threshold of nr errors). In addition  to  alerting
       all  operators  implied by the -n key, dump interacts with the operator
       on dump's control 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,
       restart	itself from the checkpoint after the old tape has been rewound
       and removed, and a new tape has been mounted.

       Dump tells the operator what is going on at periodic intervals, includ‐
       ing  usually low estimates of the number of blocks to write, the number
       of tapes it will take, the time to completion, and the time to the tape
       change.	The  output  is verbose, so that others know that the terminal
       controlling dump is busy, and will be for some time.

       In the event of a catastrophic disk event, the time required to restore
       all  the necessary backup tapes or files to disk can be kept to a mini‐
       mum by staggering the incremental dumps. An efficient method  of	 stag‐
       gering incremental dumps to minimize the number of tapes follows:

       —      Always start with a level 0 backup, for example:
		     /sbin/dump -0u -f /dev/st0 /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 for‐
	      ever.

       —      After  a	level  0,  dumps of active file systems are taken on a
	      daily basis, 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 number
	      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.

       Another	backup	strategy  is the Tower of Hanoi sequence, which reuses
       older tapes in a way that for newer dates the available restore	points
       are     more	frequent,     then     for     older	 dates	  (see
       http://en.wikipedia.org/wiki/Backup_rotation_scheme   for    additional
       information).

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

ENVIRONMENT
       TAPE   If no -f option was specified, dump will use the	device	speci‐
	      fied via TAPE as the dump device.	 TAPE may be of the form tape‐
	      name, host:tapename, or user@host:tapename.

       RMT    The environment variable RMT will be used to determine the path‐
	      name of the remote rmt(8) program.

       RSH    Dump uses the contents of this variable to determine the name of
	      the remote shell command to use when doing remote backups	 (rsh,
	      ssh  etc.).  If  this variable is not set, rcmd(3) will be used,
	      but only root will be able to do remote backups.

FILES
       /dev/st0
	      default tape unit to dump to

       /etc/dumpdates
	      dump date records

       /etc/fstab
	      dump table: file systems and frequency

       /etc/mtab
	      dump table: mounted file systems

       /etc/group
	      to find group operator

SEE ALSO
       fstab(5), restore(8), rmt(8)

DIAGNOSTICS
       Many, and verbose.

COMPATIBILITY
       The format of the /etc/dumpdates file has changed  in  release  0.4b34,
       however,	 the  file  will  be  read correctly with either pre-0.4b34 or
       0.4b34 and later versions of dump provided that the  machine  on	 which
       dump  is	 run  did  not change timezones (which should be a fairly rare
       occurrence).

EXIT STATUS
       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
       It might be considered a bug that this version of dump can only	handle
       ext2/3/4 filesystems.  Specifically, it does not work with FAT filesys‐
       tems.

       Fewer than 32 read errors (change this with -I) on the  filesystem  are
       ignored. If noticing read errors is important, the output from dump can
       be parsed to look for lines that contain the text 'read error'.

       When a read error occurs, dump prints out  the  corresponding  physical
       disk  block and sector number and the ext2/3/4 logical block number. It
       doesn't print out the corresponding file name or even the inode number.
       The user has to use debugfs(8), commands ncheck and icheck to translate
       the ext2blk number printed out by dump into an inode number, then  into
       a file name.

       Each reel requires a new process, so parent processes for reels already
       written just hang around until the entire tape is written.

       The estimated number of tapes is not correct if compression is on.

       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
       provided more assistance for the operator running restore.

       Dump cannot do remote backups without being run as  root,  due  to  its
       security	 history.   Presently,	it works if you set it setuid (like it
       used to be), but this might constitute a security risk. Note  that  you
       can set RSH to use a remote shell program instead.

AUTHOR
       The  dump/restore  backup  suite	 was ported to Linux's Second Extended
       File System by Remy Card <card@Linux.EU.Org>. He maintained the initial
       versions of dump (up and including 0.4b4, released in January 1997).

       Starting	   with	  0.4b5,   the	 new   maintainer   is	 Stelian   Pop
       <stelian@popies.net>.

AVAILABILITY
       The dump/restore backup suite is	 available  from  <http://dump.source‐
       forge.net>

HISTORY
       A dump command appeared in Version 6 AT&T UNIX.

BSD			version 0.4b44 of June 10, 2011		       DUMP(8)
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