Provided by: dump_0.4b46-5_amd64 bug

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 operator 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 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
              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 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 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
              /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
       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 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 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 specified via TAPE  as  the
              dump   device.    TAPE   may   be   of   the   form   tapename,  host:tapename,  or
              user@host:tapename.

       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.

FILES

       /dev/st0
              default tape unit to dump to

       /var/lib/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 /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).

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 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
       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.sourceforge.net>

HISTORY

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