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33 .\" $Id: dump.8.in,v 1.24 2001/03/28 12:59:48 stelian Exp $
37 .Os "dump __VERSION__"
40 .Nd ext2 filesystem backup
43 .Op Fl 0123456789ackMnSu
47 .Op Fl e Ar inode number
54 .Op Fl z Ar compression level
62 option syntax is implemented for backward compatibility but
63 is not documented here.)
68 and determines which files
69 need to be backed up. These files
70 are copied to the given disk, tape or other
71 storage medium for safe keeping (see the
73 option below for doing remote backups).
74 A dump that is larger than the output medium is broken into
76 On most media the size is determined by writing until an
77 end-of-media indication is returned.
79 On media that cannot reliably return an end-of-media indication
80 (such as some cartridge tape drives), each volume is of a fixed size;
81 the actual size is determined by specifying cartridge media, or via the
82 tape size, density and/or block count options below.
83 By default, the same output file name is used for each volume
84 after prompting the operator to change media.
87 is either a mountpoint of a filesystem
88 or a directory to be backed up as a subset of a filesystem.
89 In the former case, either the path to a mounted filesystem
90 or the device of an unmounted filesystem can be used.
91 In the latter case, certain restrictions are placed on the backup:
93 is not allowed and the only dump level that is supported is
96 The following options are supported by
101 A level 0, full backup,
102 guarantees the entire file system is copied
106 A level number above 0,
111 copy all files new or modified since the
112 last dump of a lower level.
113 The default level is 9.
115 The number of 1 kB blocks per volume.
116 This option overrides the end-of-media detection, and calculation
117 of tape size based on length and density.
120 Bypass all tape length calculations, and write
121 until an end-of-media indication is returned. This works best
122 for most modern tape drives, and is the default.
123 Use of this option is particularly recommended when appending to an
124 existing tape, or using a tape drive with hardware compression
125 (where you can never be sure about the compression ratio).
126 .It Fl b Ar blocksize
127 The number of kilobytes per dump record.
128 Since the IO system slices all requests into chunks of MAXBSIZE
129 (typically 64kB), it is not possible to use a larger blocksize
130 without having problems later with
134 will constrain writes to MAXBSIZE.
135 The default blocksize is 10.
137 Change the defaults for use with a cartridge tape drive, with a density
138 of 8000 bpi, and a length of 1700 feet. Specifying a cartridge drive
139 overrides the end-of-media detection.
143 from the dump (you can use
145 to find the inode number for a file or directory).
151 only for dumps at or above the given
153 The default honor level is 1,
154 so that incremental backups omit such files
155 but full backups retain them.
159 The default is 1600BPI. Specifying a tape density overrides the
160 end-of-media detection.
165 may be a special device file
170 (a floppy disk drive),
174 (the standard output).
175 Multiple file names may be given as a single argument separated by commas.
176 Each file will be used for one dump volume in the order listed;
177 if the dump requires more volumes than the number of names given,
178 the last file name will used for all remaining volumes after prompting
180 If the name of the file is of the form
185 writes to the named file on the remote host using
187 The default path name of the remote
190 .\" rmt path, is the path on the remote host
192 this can be overridden by the environment variable
195 Run script at the end of each tape. The device name and the
196 current volume number are passed on the command line.
197 The script must return 0 if
199 should continue without asking the user to change the tape, 1 if
201 dump should continue but ask the user to change the tape.
202 Any other exit code will cause
205 For security reasons,
207 reverts back to the real user ID and the real group ID before
210 Use Kerberos authentication to talk to remote tape servers. (Only
211 available if this option was enabled when
215 The user-supplied text string
217 is placed into the dump header, where tools like
222 Note that this label is limited
223 to be at most LBLSIZE (currently 16) characters, which must include
227 Enable the multi-volume feature. The name specified with
229 is treated as a prefix and
231 writes in sequence to <prefix>001, <prefix>002 etc. This can be
232 useful when dumping to files on an ext2 partition, in order to bypass
233 the 2GB file size limitation.
237 requires operator attention,
238 notify all operators in the group
240 by means similar to a
243 Attempt to calculate the amount of tape needed at a particular density.
244 If this amount is exceeded,
246 prompts for a new tape.
247 It is recommended to be a bit conservative on this option.
248 The default tape length is 2300 feet. Specifying the tape size
249 overrides end-of-media detection.
252 Size estimate. Determine the amount of space
253 that is needed to perform the dump without
254 actually doing it, and display the estimated
255 number of bytes it will take. This is useful
256 with incremental dumps to determine how many
257 volumes of media will be needed.
259 Use the specified date as the starting time for the dump
260 instead of the time determined from looking in
264 is the same as that of
266 This option is useful for automated dump scripts that wish to
267 dump over a specific period of time.
270 option is mutually exclusive from the
276 after a successful dump.
279 is readable by people, consisting of one
280 free format record per line:
286 There may be only one entry per filesystem at each level.
289 may be edited to change any of the fields,
293 tells the operator what file systems need to be dumped.
294 This information is gleaned from the files
302 to print out, for all file systems in
304 and regognized file systems in
306 the most recent dump date and level,
307 and highlights those that should be dumped.
310 option is set, all other options are ignored, and
316 but prints only recognized filesystems in
318 which need to be dumped.
319 .It Fl z Ar compression level
320 Compress every block to be written on the tape using zlib library. This
321 option will work only when dumping to a file or pipe or, when dumping
322 to a tape drive, if the tape drive is capable of writing variable
323 length blocks. You will need at least the 0.4b22 version of restore in
324 order to extract compressed tapes. Tapes written using compression will
325 not be compatible with the BSD tape format. The (optional) parameter
326 specifies the compression level zlib will use. The default compression
331 requires operator intervention on these conditions:
336 disk read error (if there is more than a threshold of 32).
337 In addition to alerting all operators implied by the
341 interacts with the operator on
343 control terminal at times when
345 can no longer proceed,
346 or if something is grossly wrong.
351 be answered by typing
357 Since making a dump involves a lot of time and effort for full dumps,
359 checkpoints itself at the start of each tape volume.
360 If writing that volume fails for some reason,
363 with operator permission,
364 restart itself from the checkpoint
365 after the old tape has been rewound and removed,
366 and a new tape has been mounted.
369 tells the operator what is going on at periodic intervals,
370 including usually low estimates of the number of blocks to write,
371 the number of tapes it will take, the time to completion, and
372 the time to the tape change.
373 The output is verbose,
374 so that others know that the terminal
378 and will be for some time.
380 In the event of a catastrophic disk event, the time required
381 to restore all the necessary backup tapes or files to disk
382 can be kept to a minimum by staggering the incremental dumps.
383 An efficient method of staggering incremental dumps
384 to minimize the number of tapes follows:
385 .Bl -bullet -offset indent
387 Always start with a level 0 backup, for example:
388 .Bd -literal -offset indent
389 /sbin/dump -0u -f /dev/st0 /usr/src
392 This should be done at set intervals, say once a month or once every two months,
393 and on a set of fresh tapes that is saved forever.
395 After a level 0, dumps of active file
396 systems are taken on a daily basis,
397 using a modified Tower of Hanoi algorithm,
398 with this sequence of dump levels:
399 .Bd -literal -offset indent
400 3 2 5 4 7 6 9 8 9 9 ...
403 For the daily dumps, it should be possible to use a fixed number of tapes
404 for each day, used on a weekly basis.
405 Each week, a level 1 dump is taken, and
406 the daily Hanoi sequence repeats beginning with 3.
407 For weekly dumps, another fixed set of tapes per dumped file system is
408 used, also on a cyclical basis.
411 After several months or so, the daily and weekly tapes should get
412 rotated out of the dump cycle and fresh tapes brought in.
416 If no -f option was specified,
418 will use the device specified via
426 .Qq user@host:tapename .
428 The environment variable
430 will be used to determine the pathname of the remote
435 uses the contents of this variable to determine the name of the
436 remote shell command to use when doing remote backups (rsh, ssh etc.).
437 If this variable is not set,
439 will be used, but only root will be able to do remote backups.
441 .Bl -tag -width __DUMPDATES__ -compact
443 default tape unit to dump to
447 dump table: file systems and frequency
460 exits with zero status on success.
461 Startup errors are indicated with an exit code of 1;
462 abnormal termination is indicated with an exit code of 3.
464 It might be considered a bug that this version of dump can only handle ext2
465 filesystems. Specifically, it does not work with FAT filesystems.
467 Fewer than 32 read errors on the filesystem are ignored. If noticing
468 read errors is important, the output from dump can be parsed to look for lines
469 that contain the text 'read error'.
471 Each reel requires a new process, so parent processes for
472 reels already written just hang around until the entire tape
477 knew about the dump sequence,
478 kept track of the tapes scribbled on,
479 told the operator which tape to mount when,
480 and provided more assistance
481 for the operator running
485 cannot do remote backups without being run as root, due to its
487 Presently, it works if you set it setuid (like it used to be), but this
488 might constitute a security risk. Note that you can set RSH to use
489 a remote shell program instead.
493 backup suite was ported to Linux's Second Extended File System
494 by Remy Card <card@Linux.EU.Org>. He maintained the initial versions
495 of dump (up and including 0.4b4, released in january 1997).
497 Starting with 0.4b5, the new maintainer is Stelian Pop
503 backup suite is available from
505 http://dump.sourceforge.net