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33 .\" $Id: dump.8.in,v 1.31 2001/08/16 09:37:59 stelian Exp $
37 .Os "dump __VERSION__"
40 .Nd ext2 filesystem backup
43 .Op Fl 0123456789ackMnqSu
47 .Op Fl e Ar inode numbers
56 .Op Fl z Ar compression level
64 option syntax is implemented for backward compatibility but
65 is not documented here.)
70 and determines which files
71 need to be backed up. These files
72 are copied to the given disk, tape or other
73 storage medium for safe keeping (see the
75 option below for doing remote backups).
76 A dump that is larger than the output medium is broken into
78 On most media the size is determined by writing until an
79 end-of-media indication is returned.
81 On media that cannot reliably return an end-of-media indication
82 (such as some cartridge tape drives), each volume is of a fixed size;
83 the actual size is determined by specifying cartridge media, or via the
84 tape size, density and/or block count options below.
85 By default, the same output file name is used for each volume
86 after prompting the operator to change media.
89 is either a mountpoint of a filesystem
90 or a list of files and directories to be backed up as a subset of a
92 In the former case, either the path to a mounted filesystem
93 or the device of an unmounted filesystem can be used.
94 In the latter case, certain restrictions are placed on the backup:
96 is not allowed, the only dump level that is supported is
98 and all the files and directories must reside on the same filesystem.
100 The following options are supported by
105 A level 0, full backup,
106 guarantees the entire file system is copied
110 A level number above 0,
115 copy all files new or modified since the
116 last dump of a lower level.
117 The default level is 9.
119 The number of 1 kB blocks per volume.
120 This option overrides the end-of-media detection, and calculation
121 of tape size based on length and density. If compression is on this
122 limits the size of the compressed output per volume.
125 Bypass all tape length calculations, and write
126 until an end-of-media indication is returned. This works best
127 for most modern tape drives, and is the default.
128 Use of this option is particularly recommended when appending to an
129 existing tape, or using a tape drive with hardware compression
130 (where you can never be sure about the compression ratio).
131 .It Fl b Ar blocksize
132 The number of kilobytes per dump record.
133 Since the IO system slices all requests into chunks of MAXBSIZE
134 (typically 64kB), it is not possible to use a larger blocksize
135 without having problems later with
139 will constrain writes to MAXBSIZE.
140 The default blocksize is 10.
142 Change the defaults for use with a cartridge tape drive, with a density
143 of 8000 bpi, and a length of 1700 feet. Specifying a cartridge drive
144 overrides the end-of-media detection.
150 parameter is a comma separated list of inode numbers (you can use
152 to find the inode number for a file or directory).
154 Read list of inodes to be excluded from the dump from the text file
158 should be an ordinary file containing inode numbers separated by
165 only for dumps at or above the given
167 The default honor level is 1,
168 so that incremental backups omit such files
169 but full backups retain them.
173 The default is 1600BPI. Specifying a tape density overrides the
174 end-of-media detection.
179 may be a special device file
184 (a floppy disk drive),
188 (the standard output).
189 Multiple file names may be given as a single argument separated by commas.
190 Each file will be used for one dump volume in the order listed;
191 if the dump requires more volumes than the number of names given,
192 the last file name will used for all remaining volumes after prompting
194 If the name of the file is of the form
199 writes to the named file on the remote host using
201 The default path name of the remote
204 .\" rmt path, is the path on the remote host
206 this can be overridden by the environment variable
209 Run script at the end of each tape. The device name and the
210 current volume number are passed on the command line.
211 The script must return 0 if
213 should continue without asking the user to change the tape, 1 if
215 should continue but ask the user to change the tape.
216 Any other exit code will cause
219 For security reasons,
221 reverts back to the real user ID and the real group ID before
224 Use Kerberos authentication to talk to remote tape servers. (Only
225 available if this option was enabled when
229 The user-supplied text string
231 is placed into the dump header, where tools like
236 Note that this label is limited
237 to be at most LBLSIZE (currently 16) characters, which must include
241 Enable the multi-volume feature. The name specified with
243 is treated as a prefix and
245 writes in sequence to <prefix>001, <prefix>002 etc. This can be
246 useful when dumping to files on an ext2 partition, in order to bypass
247 the 2GB file size limitation.
251 requires operator attention,
252 notify all operators in the group
254 by means similar to a
259 abort immediately whenever operator attention is required,
260 without prompting in case of write errors, tape changes etc.
262 Enable the Quick File Access support. Tape positions for each
263 inode are stored into the file
265 which is used by restore (if called with parameter Q and the filename)
266 to directly position the tape at the file restore is currently working
267 on. This saves hours when restoring single files from large backups,
268 saves the tapes and the drive's head.
270 It is recommended to set up the st driver to return logical tape
271 positions rather than physical before calling dump/restore with
272 parameter Q. Since not all tape devices support physical tape
273 positions those tape devices return an error during dump/restore when
274 the st driver is set to the default physical setting.
275 Please see the st man page, option MTSETDRVBUFFER, or the mt man
276 page, on how to set the driver to return logical tape positions.
278 Before calling restore with parameter Q, always make sure the st
279 driver is set to return the same type of tape position used during the
280 call to dump. Otherwise restore may be confused.
282 Attempt to calculate the amount of tape needed at a particular density.
283 If this amount is exceeded,
285 prompts for a new tape.
286 It is recommended to be a bit conservative on this option.
287 The default tape length is 2300 feet. Specifying the tape size
288 overrides end-of-media detection.
291 Size estimate. Determine the amount of space
292 that is needed to perform the dump without
293 actually doing it, and display the estimated
294 number of bytes it will take. This is useful
295 with incremental dumps to determine how many
296 volumes of media will be needed.
298 Use the specified date as the starting time for the dump
299 instead of the time determined from looking in
303 is the same as that of
305 This option is useful for automated dump scripts that wish to
306 dump over a specific period of time.
309 option is mutually exclusive from the
315 after a successful dump.
318 is readable by people, consisting of one
319 free format record per line:
325 There may be only one entry per filesystem at each level.
328 may be edited to change any of the fields,
332 tells the operator what file systems need to be dumped.
333 This information is gleaned from the files
341 to print out, for all file systems in
343 and regognized file systems in
345 the most recent dump date and level,
346 and highlights those that should be dumped.
349 option is set, all other options are ignored, and
355 but prints only recognized filesystems in
357 which need to be dumped.
358 .It Fl z Ar compression level
359 Compress every block to be written on the tape using zlib library. This
360 option will work only when dumping to a file or pipe or, when dumping
361 to a tape drive, if the tape drive is capable of writing variable
362 length blocks. You will need at least the 0.4b22 version of restore in
363 order to extract compressed tapes. Tapes written using compression will
364 not be compatible with the BSD tape format. The (optional) parameter
365 specifies the compression level zlib will use. The default compression
370 requires operator intervention on these conditions:
375 disk read error (if there is more than a threshold of 32).
376 In addition to alerting all operators implied by the
380 interacts with the operator on
382 control terminal at times when
384 can no longer proceed,
385 or if something is grossly wrong.
390 be answered by typing
396 Since making a dump involves a lot of time and effort for full dumps,
398 checkpoints itself at the start of each tape volume.
399 If writing that volume fails for some reason,
402 with operator permission,
403 restart itself from the checkpoint
404 after the old tape has been rewound and removed,
405 and a new tape has been mounted.
408 tells the operator what is going on at periodic intervals,
409 including usually low estimates of the number of blocks to write,
410 the number of tapes it will take, the time to completion, and
411 the time to the tape change.
412 The output is verbose,
413 so that others know that the terminal
417 and will be for some time.
419 In the event of a catastrophic disk event, the time required
420 to restore all the necessary backup tapes or files to disk
421 can be kept to a minimum by staggering the incremental dumps.
422 An efficient method of staggering incremental dumps
423 to minimize the number of tapes follows:
424 .Bl -bullet -offset indent
426 Always start with a level 0 backup, for example:
427 .Bd -literal -offset indent
428 /sbin/dump -0u -f /dev/st0 /usr/src
431 This should be done at set intervals, say once a month or once every two months,
432 and on a set of fresh tapes that is saved forever.
434 After a level 0, dumps of active file
435 systems are taken on a daily basis,
436 using a modified Tower of Hanoi algorithm,
437 with this sequence of dump levels:
438 .Bd -literal -offset indent
439 3 2 5 4 7 6 9 8 9 9 ...
442 For the daily dumps, it should be possible to use a fixed number of tapes
443 for each day, used on a weekly basis.
444 Each week, a level 1 dump is taken, and
445 the daily Hanoi sequence repeats beginning with 3.
446 For weekly dumps, another fixed set of tapes per dumped file system is
447 used, also on a cyclical basis.
450 After several months or so, the daily and weekly tapes should get
451 rotated out of the dump cycle and fresh tapes brought in.
455 If no -f option was specified,
457 will use the device specified via
465 .Qq user@host:tapename .
467 The environment variable
469 will be used to determine the pathname of the remote
474 uses the contents of this variable to determine the name of the
475 remote shell command to use when doing remote backups (rsh, ssh etc.).
476 If this variable is not set,
478 will be used, but only root will be able to do remote backups.
480 .Bl -tag -width __DUMPDATES__ -compact
482 default tape unit to dump to
486 dump table: file systems and frequency
499 exits with zero status on success.
500 Startup errors are indicated with an exit code of 1;
501 abnormal termination is indicated with an exit code of 3.
503 It might be considered a bug that this version of dump can only handle ext2
504 filesystems. Specifically, it does not work with FAT filesystems.
506 Fewer than 32 read errors on the filesystem are ignored. If noticing
507 read errors is important, the output from dump can be parsed to look for lines
508 that contain the text 'read error'.
510 Each reel requires a new process, so parent processes for
511 reels already written just hang around until the entire tape
514 The estimated number of tapes is not correct if compression is on.
518 knew about the dump sequence,
519 kept track of the tapes scribbled on,
520 told the operator which tape to mount when,
521 and provided more assistance
522 for the operator running
526 cannot do remote backups without being run as root, due to its
528 Presently, it works if you set it setuid (like it used to be), but this
529 might constitute a security risk. Note that you can set RSH to use
530 a remote shell program instead.
534 backup suite was ported to Linux's Second Extended File System
535 by Remy Card <card@Linux.EU.Org>. He maintained the initial versions
536 of dump (up and including 0.4b4, released in january 1997).
538 Starting with 0.4b5, the new maintainer is Stelian Pop
544 backup suite is available from
546 http://dump.sourceforge.net