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33 .\" $Id: dump.8.in,v 1.5 1999/11/22 19:08:50 tiniou Exp $
37 .Os "dump __VERSION__"
40 .Nd ext2 filesystem backup
43 .Op Fl 0123456789acknSu
54 .Op Fl 0123456789acknSu
70 option syntax is implemented for backward compatibility but
71 is not documented here.)
76 and determines which files
77 need to be backed up. These files
78 are copied to the given disk, tape or other
79 storage medium for safe keeping (see the
81 option below for doing remote backups).
82 A dump that is larger than the output medium is broken into
84 On most media the size is determined by writing until an
85 end-of-media indication is returned. This can be enforced
90 On media that cannot reliably return an end-of-media indication
91 (such as some cartridge tape drives),
92 each volume is of a fixed size;
93 the actual size is determined by the tape size, density and/or
94 block count options below.
95 By default, the same output file name is used for each volume
96 after prompting the operator to change media.
98 The following options are supported by
103 A level 0, full backup,
104 guarantees the entire file system is copied
108 A level number above 0,
113 copy all files new or modified since the
114 last dump of the same or lower level.
115 The default level is 9.
117 The number of 1 KB blocks per volume.
118 This option overrides the calculation of tape size
119 based on length and density.
122 Bypass all tape length considerations, and enforce writing
123 until an end-of-media indication is returned. This fits best
124 for most modern tape drives. Use of this option is particularly
125 recommended when appending to an existing tape, or using a tape
126 drive with hardware compression (where you can never be sure about
127 the compression ratio).
128 .It Fl b Ar blocksize
129 The number of kilobytes per dump record.
130 Since the IO system slices all requests into chunks of MAXBSIZE
131 (typically 64KB), it is not possible to use a larger blocksize
132 without having problems later with
136 will constrain writes to MAXBSIZE.
138 Change the defaults for use with a cartridge tape drive, with a density
139 of 8000 bpi, and a length of 1700 feet.
145 only for dumps at or above the given
147 The default honor level is 1,
148 so that incremental backups omit such files
149 but full backups retain them.
153 The default is 1600BPI.
158 may be a special device file
163 (a floppy disk drive),
167 (the standard output).
168 Multiple file names may be given as a single argument separated by commas.
169 Each file will be used for one dump volume in the order listed;
170 if the dump requires more volumes than the number of names given,
171 the last file name will used for all remaining volumes after prompting
173 If the name of the file is of the form
178 writes to the named file on the remote host using
180 The default path name of the remote
183 .\" rmt path, is the path on the remote host
185 this can be overridden by the environment variable
188 Use Kerberos authentication to talk to remote tape servers. (Only
189 available if this option was enabled when
193 The user-supplied text string
195 is placed into the dump header, where tools like
200 Note that this label is limited
201 to be at most LBLSIZE (currently 16) characters, which must include
207 requires operator attention,
208 notify all operators in the group
210 by means similar to a
213 Attempt to calculate the amount of tape needed
214 at a particular density.
215 If this amount is exceeded,
217 prompts for a new tape.
218 It is recommended to be a bit conservative on this option.
219 The default tape length is 2300 feet.
222 Size estimate. Determine the amount of space
223 that is needed to perform the dump without
224 actually doing it, and display the estimated
225 number of blocks it will take. This is useful
226 with incremental dumps to determine how many
227 volumes of media will be needed.
229 Use the specified date as the starting time for the dump
230 instead of the time determined from looking in
234 is the same as that of
236 This option is useful for automated dump scripts that wish to
237 dump over a specific period of time.
240 option is mutually exclusive from the
246 after a successful dump.
249 is readable by people, consisting of one
250 free format record per line:
256 There may be only one entry per filesystem at each level.
259 may be edited to change any of the fields,
263 tells the operator what file systems need to be dumped.
264 This information is gleaned from the files
272 to print out, for each file system in
274 the most recent dump date and level,
275 and highlights those file systems that should be dumped.
278 option is set, all other options are ignored, and
284 but prints only those filesystems which need to be dumped.
288 requires operator intervention on these conditions:
293 disk read error (if there is more than a threshold of 32).
294 In addition to alerting all operators implied by the
298 interacts with the operator on
300 control terminal at times when
302 can no longer proceed,
303 or if something is grossly wrong.
308 be answered by typing
314 Since making a dump involves a lot of time and effort for full dumps,
316 checkpoints itself at the start of each tape volume.
317 If writing that volume fails for some reason,
320 with operator permission,
321 restart itself from the checkpoint
322 after the old tape has been rewound and removed,
323 and a new tape has been mounted.
326 tells the operator what is going on at periodic intervals,
327 including usually low estimates of the number of blocks to write,
328 the number of tapes it will take, the time to completion, and
329 the time to the tape change.
330 The output is verbose,
331 so that others know that the terminal
335 and will be for some time.
337 In the event of a catastrophic disk event, the time required
338 to restore all the necessary backup tapes or files to disk
339 can be kept to a minimum by staggering the incremental dumps.
340 An efficient method of staggering incremental dumps
341 to minimize the number of tapes follows:
342 .Bl -bullet -offset indent
344 Always start with a level 0 backup, for example:
345 .Bd -literal -offset indent
346 /sbin/dump -0u -f /dev/st0 /usr/src
349 This should be done at set intervals, say once a month or once every two months,
350 and on a set of fresh tapes that is saved forever.
352 After a level 0, dumps of active file
353 systems are taken on a daily basis,
354 using a modified Tower of Hanoi algorithm,
355 with this sequence of dump levels:
356 .Bd -literal -offset indent
357 3 2 5 4 7 6 9 8 9 9 ...
360 For the daily dumps, it should be possible to use a fixed number of tapes
361 for each day, used on a weekly basis.
362 Each week, a level 1 dump is taken, and
363 the daily Hanoi sequence repeats beginning with 3.
364 For weekly dumps, another fixed set of tapes per dumped file system is
365 used, also on a cyclical basis.
368 After several months or so, the daily and weekly tapes should get
369 rotated out of the dump cycle and fresh tapes brought in.
373 If no -f option was specified,
375 will use the device specified via
383 .Qq user@host:tapename .
385 The environment variable
387 will be used to determine the pathname of the remote
392 uses the contents of this variable to determine the name of the
393 remote shell command to use when doing remote backups (rsh, ssh etc.).
394 If this variable is not set,
396 will be used, but only root will be able to do remote backups.
398 .Bl -tag -width __DUMPDATES__ -compact
400 default tape unit to dump to
404 dump table: file systems and frequency
417 exits with zero status on success.
418 Startup errors are indicated with an exit code of 1;
419 abnormal termination is indicated with an exit code of 3.
421 It might be considered a bug that this version of dump can only handle ext2
422 filesystems. Specifically, it does not work with FAT filesystems.
424 Fewer than 32 read errors on the filesystem are ignored. If noticing
425 read errors is important, the output from dump can be parsed to look for lines
426 that contain the text 'read error'.
428 Each reel requires a new process, so parent processes for
429 reels already written just hang around until the entire tape
437 option does not report filesystems that have never been recorded
445 knew about the dump sequence,
446 kept track of the tapes scribbled on,
447 told the operator which tape to mount when,
448 and provided more assistance
449 for the operator running
453 cannot do remote backups without being run as root, due to its
455 Presently, it works if you set it setuid (like it used to be), but this
456 might constitute a security risk. Note that you can set RSH to use
457 a remote shell program instead.
461 backup suit was ported to Linux's Second Extended File System
462 by Remy Card <card@Linux.EU.Org>. He maintained the initial versions
463 of dump (up and including 0.4b4, released in january 1997).
465 Starting with 0.4b5, the new maintainer is Stelian Pop
471 backup suit is available for anonymous ftp from tsx-11.mit.edu
472 in /pub/linux/ALPHA/ext2fs (development versions) or
473 /pub/linux/packages/ext2fs (stable versions).
475 An alternate downloading location is http://perso.cybercable.fr/pop/dump.