Provided by: dump_0.4b47-4_amd64 bug


       dump - ext2/3/4 filesystem backup


       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]

       dump [-W | -w]


       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 operator to
       change media.

       files-to-dump can be a filesystem identifier or a list of  files  and  directories  to  be
       backed up.

       A  filesystem can be identified by its device path (e.g.  /dev/sde2), by its mountpoint if
       the filesystem is currently mounted (e.g.  /var), or by its label or uuid property if  the
       block device is known to blkid(8) (e.g.  LABEL=foobar or UUID=a0f155-...).

       If  files-to-dump  is a list of files and directories, then certain restrictions apply: -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.


       The following options are supported by dump:

              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

       -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 density 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
              density.  If  compression  is  on this limits the size of the compressed 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 /var/lib/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

       -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 prompting 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 incremental 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 compressed tapes.  Tapes  written
              using  compression  will not be compatible with the BSD tape format. The (optional)
              parameter specifies the compression level bzlib will use. The  default  compression
              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 compiled.)

       -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 compatible 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 limitation.

       -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 /var/lib/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 followed by two digits for the number of hours and two  digits  for  the
              minutes.   For  example,  -0800  for eight hours west of Greenwich 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 specific period of time. The -T option is mutually exclusive from the
              -u option.

       -u     Update  the  file  /var/lib/dumpdates  after  a  successful  dump.  The  format  of
              /var/lib/dumpdates  is  human-readable,  with one record per line. Each line holds,
              separated by spaces, a filesystem identifier, dump increment level and dump date in
              ctime(3)  format followed by a rfc822 timezone specification (see the -T 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.

              The  filesystem  identifier  is  exactly  as  given  on  the  command  line,   e.g.
              UUID=a0f155-...   or  /dev/sde2.   This  is for incremental dumps of filesystems on
              removable media or other situations where the device path changes over time.  There
              may  be  at  most  one  entry  per  filesystem  for  each increment level. The file
              /var/lib/dumpdates 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 /var/lib/dumpdates and /etc/fstab.   The  -W  option  causes
              dump to print out, for all file systems in /var/lib/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 compressed tapes. Tapes written using
              compression will not be compatible 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 compressed tapes. Tapes written using
              compression will not be  compatible  with  the  BSD  tape  format.  The  (optional)
              parameter  specifies  the  compression level zlib will use. The default compression
              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, including 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 minimum by staggering the incremental
       dumps. An efficient method of staggering incremental dumps to minimize the number of tapes

       —      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 forever.

       —      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 for additional information).

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


       TAPE   If no -f option was specified, dump will use the device specified via TAPE  as  the
              dump   device.    TAPE   may   be   of   the   form   tapename,  host:tapename,  or

       RMT    The environment variable RMT will be used to determine the pathname 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.


              default tape unit to dump to

              dump date records

              dump table: file systems and frequency

              dump table: mounted file systems

              to find group operator


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


       Many, and verbose.


       The format of the /var/lib/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).


       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.


       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 filesystems.

       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

       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.


       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 <>.


       The dump/restore backup suite is available from <>


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