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DUMP(8) 			   BSD System Manager's Manual				  DUMP(8)

     dump -- ext2 filesystem backup

     dump [-0123456789ackMnqSu] [-A file] [-B records] [-b blocksize] [-d density]
	  [-e inode numbers] [-E file] [-f file] [-F script] [-h level] [-I nr errors]
	  [-j compression level] [-L label] [-Q file] [-s feet] [-T date] [-z compression level]
     dump [-W | -w]

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

     Dump examines files on an ext2 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 car-
     tridge 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

     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, cer-
     tain 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.

     The following options are supported by dump:

     -0-9    Dump levels.  A level 0, full backup, 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 9.

     -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 exist-
	     ing 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.  Since the IO system slices all requests
	     into chunks of MAXBSIZE (typically 64kB), it is not possible to use a larger block-
	     size without having problems later with restore(8).  Therefore dump will constrain
	     writes to MAXBSIZE.  The default blocksize is 10.

     -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 vol-
	     ume.  This option overrides the calculation of tape size based on length and den-
	     sity.  If compression is on this limits the size of the compressed output per vol-

     -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

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

     -e inodes
	     Exclude inodes from the dump. The inodes parameter is a comma separated list of
	     inode numbers (you can use stat 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 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. 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 secu-
	     rity 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 only for dumps at or above the given level.  The
	     default honor level is 1, so that incremental backups omit such files but full back-
	     ups retain them.

     -I nr errors
	     By default, dump will ignore the first 32 read errors on the file system before ask-
	     ing 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.

     -j compression 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) parame-
	     ter 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(1) 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.

	     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 partition, in order to bypass the 2GB file size limita-

     -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 prompt-
	     ing 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 man page, option MTSETDRVBUFFER, or the mt 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 con-
	     servative 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

     -T date
	     Use the specified date as the starting time for the dump instead of the time deter-
	     mined from looking in /etc/dumpdates.  The format of date is the same as that of
	     ctime(3).	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 /etc/dumpdates after a successful dump.  The format 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.  There may be only
	     one entry per filesystem at each level.  The file /etc/dumpdates may be edited to
	     change any of the fields, if necessary.

     -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 regognized file systems in
	     /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

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

     -z compression 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) parame-
	     ter 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 esti-
     mates of the number of blocks to write, the number of tapes it will take, the time to com-
     pletion, 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:

	   o   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.

	   o   After a level 0, dumps of active file systems are taken on a daily basis, using a
	       modified Tower of Hanoi algorithm, 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.

     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 vari-
		 able is not set, rcmd(3) will be used, but only root will be able to do remote

     /dev/st0	     default tape unit to dump to
     /etc/dumpdates  dump date records
     /etc/fstab      dump table: file systems and frequency
     /etc/group      to find group operator

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

     Many, and verbose.

     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 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'.

     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.

dump 0.4b28				  April 12, 2002			      dump 0.4b28
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