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33 .\" $Id: dump.8.in,v 1.19 2000/12/04 15:43:16 stelian Exp $
37 .Os "dump __VERSION__"
40 .Nd ext2 filesystem backup
43 .Op Fl 0123456789ackMnSu
47 .Op Fl e Ar inode number
61 option syntax is implemented for backward compatibility but
62 is not documented here.)
67 and determines which files
68 need to be backed up. These files
69 are copied to the given disk, tape or other
70 storage medium for safe keeping (see the
72 option below for doing remote backups).
73 A dump that is larger than the output medium is broken into
75 On most media the size is determined by writing until an
76 end-of-media indication is returned.
78 On media that cannot reliably return an end-of-media indication
79 (such as some cartridge tape drives), each volume is of a fixed size;
80 the actual size is determined by specifying cartridge media, or via the
81 tape size, density and/or block count options below.
82 By default, the same output file name is used for each volume
83 after prompting the operator to change media.
86 is either a mountpoint of a filesystem
87 or a directory to be backed up as a subset of a filesystem.
88 In the former case, either the path to a mounted filesystem
89 or the device of an unmounted filesystem can be used.
90 In the latter case, certain restrictions are placed on the backup:
92 is not allowed and the only dump level that is supported is
95 The following options are supported by
100 A level 0, full backup,
101 guarantees the entire file system is copied
105 A level number above 0,
110 copy all files new or modified since the
111 last dump of a lower level.
112 The default level is 9.
114 The number of 1 KB blocks per volume.
115 This option overrides the end-of-media detection, and calculation
116 of tape size based on length and density.
119 Bypass all tape length calculations, and write
120 until an end-of-media indication is returned. This works best
121 for most modern tape drives, and is the default.
122 Use of this option is particularly recommended when appending to an
123 existing tape, or using a tape drive with hardware compression
124 (where you can never be sure about the compression ratio).
125 .It Fl b Ar blocksize
126 The number of kilobytes per dump record.
127 Since the IO system slices all requests into chunks of MAXBSIZE
128 (typically 64KB), it is not possible to use a larger blocksize
129 without having problems later with
133 will constrain writes to MAXBSIZE.
134 The default blocksize is 10.
136 Change the defaults for use with a cartridge tape drive, with a density
137 of 8000 bpi, and a length of 1700 feet. Specifying a cartridge drive
138 overrides the end-of-media detection.
142 from the dump (you can use
144 to find the inode number for a file or directory).
150 only for dumps at or above the given
152 The default honor level is 1,
153 so that incremental backups omit such files
154 but full backups retain them.
158 The default is 1600BPI. Specifying a tape density overrides the
159 end-of-media detection.
164 may be a special device file
169 (a floppy disk drive),
173 (the standard output).
174 Multiple file names may be given as a single argument separated by commas.
175 Each file will be used for one dump volume in the order listed;
176 if the dump requires more volumes than the number of names given,
177 the last file name will used for all remaining volumes after prompting
179 If the name of the file is of the form
184 writes to the named file on the remote host using
186 The default path name of the remote
189 .\" rmt path, is the path on the remote host
191 this can be overridden by the environment variable
194 Run script at the end of each tape. The device name and the
195 current volume number are passed on the command line.
196 The script must return 0 if
198 should continue without asking the user to change the tape, 1 if
200 dump should continue but ask the user to change the tape.
201 Any other exit code will cause
204 For security reasons,
206 reverts back to the real user ID and the real group ID before
209 Use Kerberos authentication to talk to remote tape servers. (Only
210 available if this option was enabled when
214 The user-supplied text string
216 is placed into the dump header, where tools like
221 Note that this label is limited
222 to be at most LBLSIZE (currently 16) characters, which must include
226 Enable the multi-volume feature. The name specified with
228 is treated as a prefix and
230 writes in sequence to <prefix>001, <prefix>002 etc. This can be
231 useful when dumping to files on an ext2 partition, in order to bypass
232 the 2GB file size limitation.
236 requires operator attention,
237 notify all operators in the group
239 by means similar to a
242 Attempt to calculate the amount of tape needed at a particular density.
243 If this amount is exceeded,
245 prompts for a new tape.
246 It is recommended to be a bit conservative on this option.
247 The default tape length is 2300 feet. Specifying the tape size
248 overrides end-of-media detection.
251 Size estimate. Determine the amount of space
252 that is needed to perform the dump without
253 actually doing it, and display the estimated
254 number of bytes it will take. This is useful
255 with incremental dumps to determine how many
256 volumes of media will be needed.
258 Use the specified date as the starting time for the dump
259 instead of the time determined from looking in
263 is the same as that of
265 This option is useful for automated dump scripts that wish to
266 dump over a specific period of time.
269 option is mutually exclusive from the
275 after a successful dump.
278 is readable by people, consisting of one
279 free format record per line:
285 There may be only one entry per filesystem at each level.
288 may be edited to change any of the fields,
292 tells the operator what file systems need to be dumped.
293 This information is gleaned from the files
301 to print out, for all file systems in
303 and regognized file systems in
305 the most recent dump date and level,
306 and highlights those that should be dumped.
309 option is set, all other options are ignored, and
315 but prints only recognized filesystems in
317 which need to be dumped.
321 requires operator intervention on these conditions:
326 disk read error (if there is more than a threshold of 32).
327 In addition to alerting all operators implied by the
331 interacts with the operator on
333 control terminal at times when
335 can no longer proceed,
336 or if something is grossly wrong.
341 be answered by typing
347 Since making a dump involves a lot of time and effort for full dumps,
349 checkpoints itself at the start of each tape volume.
350 If writing that volume fails for some reason,
353 with operator permission,
354 restart itself from the checkpoint
355 after the old tape has been rewound and removed,
356 and a new tape has been mounted.
359 tells the operator what is going on at periodic intervals,
360 including usually low estimates of the number of blocks to write,
361 the number of tapes it will take, the time to completion, and
362 the time to the tape change.
363 The output is verbose,
364 so that others know that the terminal
368 and will be for some time.
370 In the event of a catastrophic disk event, the time required
371 to restore all the necessary backup tapes or files to disk
372 can be kept to a minimum by staggering the incremental dumps.
373 An efficient method of staggering incremental dumps
374 to minimize the number of tapes follows:
375 .Bl -bullet -offset indent
377 Always start with a level 0 backup, for example:
378 .Bd -literal -offset indent
379 /sbin/dump -0u -f /dev/st0 /usr/src
382 This should be done at set intervals, say once a month or once every two months,
383 and on a set of fresh tapes that is saved forever.
385 After a level 0, dumps of active file
386 systems are taken on a daily basis,
387 using a modified Tower of Hanoi algorithm,
388 with this sequence of dump levels:
389 .Bd -literal -offset indent
390 3 2 5 4 7 6 9 8 9 9 ...
393 For the daily dumps, it should be possible to use a fixed number of tapes
394 for each day, used on a weekly basis.
395 Each week, a level 1 dump is taken, and
396 the daily Hanoi sequence repeats beginning with 3.
397 For weekly dumps, another fixed set of tapes per dumped file system is
398 used, also on a cyclical basis.
401 After several months or so, the daily and weekly tapes should get
402 rotated out of the dump cycle and fresh tapes brought in.
406 If no -f option was specified,
408 will use the device specified via
416 .Qq user@host:tapename .
418 The environment variable
420 will be used to determine the pathname of the remote
425 uses the contents of this variable to determine the name of the
426 remote shell command to use when doing remote backups (rsh, ssh etc.).
427 If this variable is not set,
429 will be used, but only root will be able to do remote backups.
431 .Bl -tag -width __DUMPDATES__ -compact
433 default tape unit to dump to
437 dump table: file systems and frequency
450 exits with zero status on success.
451 Startup errors are indicated with an exit code of 1;
452 abnormal termination is indicated with an exit code of 3.
454 It might be considered a bug that this version of dump can only handle ext2
455 filesystems. Specifically, it does not work with FAT filesystems.
457 Fewer than 32 read errors on the filesystem are ignored. If noticing
458 read errors is important, the output from dump can be parsed to look for lines
459 that contain the text 'read error'.
461 Each reel requires a new process, so parent processes for
462 reels already written just hang around until the entire tape
467 knew about the dump sequence,
468 kept track of the tapes scribbled on,
469 told the operator which tape to mount when,
470 and provided more assistance
471 for the operator running
475 cannot do remote backups without being run as root, due to its
477 Presently, it works if you set it setuid (like it used to be), but this
478 might constitute a security risk. Note that you can set RSH to use
479 a remote shell program instead.
483 backup suit was ported to Linux's Second Extended File System
484 by Remy Card <card@Linux.EU.Org>. He maintained the initial versions
485 of dump (up and including 0.4b4, released in january 1997).
487 Starting with 0.4b5, the new maintainer is Stelian Pop
493 backup suit is available from
495 http://dump.sourceforge.net