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33 .\" $Id: dump.8.in,v 1.25 2001/04/10 12:46:53 stelian Exp $
37 .Os "dump __VERSION__"
40 .Nd ext2 filesystem backup
43 .Op Fl 0123456789ackMnSu
47 .Op Fl e Ar inode number
55 .Op Fl z Ar compression level
63 option syntax is implemented for backward compatibility but
64 is not documented here.)
69 and determines which files
70 need to be backed up. These files
71 are copied to the given disk, tape or other
72 storage medium for safe keeping (see the
74 option below for doing remote backups).
75 A dump that is larger than the output medium is broken into
77 On most media the size is determined by writing until an
78 end-of-media indication is returned.
80 On media that cannot reliably return an end-of-media indication
81 (such as some cartridge tape drives), each volume is of a fixed size;
82 the actual size is determined by specifying cartridge media, or via the
83 tape size, density and/or block count options below.
84 By default, the same output file name is used for each volume
85 after prompting the operator to change media.
88 is either a mountpoint of a filesystem
89 or a directory to be backed up as a subset of a filesystem.
90 In the former case, either the path to a mounted filesystem
91 or the device of an unmounted filesystem can be used.
92 In the latter case, certain restrictions are placed on the backup:
94 is not allowed and the only dump level that is supported is
97 The following options are supported by
102 A level 0, full backup,
103 guarantees the entire file system is copied
107 A level number above 0,
112 copy all files new or modified since the
113 last dump of a lower level.
114 The default level is 9.
116 The number of 1 kB blocks per volume.
117 This option overrides the end-of-media detection, and calculation
118 of tape size based on length and density.
121 Bypass all tape length calculations, and write
122 until an end-of-media indication is returned. This works best
123 for most modern tape drives, and is the default.
124 Use of this option is particularly recommended when appending to an
125 existing tape, or using a tape drive with hardware compression
126 (where you can never be sure about the compression ratio).
127 .It Fl b Ar blocksize
128 The number of kilobytes per dump record.
129 Since the IO system slices all requests into chunks of MAXBSIZE
130 (typically 64kB), it is not possible to use a larger blocksize
131 without having problems later with
135 will constrain writes to MAXBSIZE.
136 The default blocksize is 10.
138 Change the defaults for use with a cartridge tape drive, with a density
139 of 8000 bpi, and a length of 1700 feet. Specifying a cartridge drive
140 overrides the end-of-media detection.
144 from the dump (you can use
146 to find the inode number for a file or directory).
152 only for dumps at or above the given
154 The default honor level is 1,
155 so that incremental backups omit such files
156 but full backups retain them.
160 The default is 1600BPI. Specifying a tape density overrides the
161 end-of-media detection.
166 may be a special device file
171 (a floppy disk drive),
175 (the standard output).
176 Multiple file names may be given as a single argument separated by commas.
177 Each file will be used for one dump volume in the order listed;
178 if the dump requires more volumes than the number of names given,
179 the last file name will used for all remaining volumes after prompting
181 If the name of the file is of the form
186 writes to the named file on the remote host using
188 The default path name of the remote
191 .\" rmt path, is the path on the remote host
193 this can be overridden by the environment variable
196 Run script at the end of each tape. The device name and the
197 current volume number are passed on the command line.
198 The script must return 0 if
200 should continue without asking the user to change the tape, 1 if
202 dump should continue but ask the user to change the tape.
203 Any other exit code will cause
206 For security reasons,
208 reverts back to the real user ID and the real group ID before
211 Use Kerberos authentication to talk to remote tape servers. (Only
212 available if this option was enabled when
216 The user-supplied text string
218 is placed into the dump header, where tools like
223 Note that this label is limited
224 to be at most LBLSIZE (currently 16) characters, which must include
228 Enable the multi-volume feature. The name specified with
230 is treated as a prefix and
232 writes in sequence to <prefix>001, <prefix>002 etc. This can be
233 useful when dumping to files on an ext2 partition, in order to bypass
234 the 2GB file size limitation.
238 requires operator attention,
239 notify all operators in the group
241 by means similar to a
244 Enable the Quick File Access support. Tape positions for each
245 inode are stored into the file
247 which is used by restore (if called with parameter Q and the filename)
248 to directly position the tape at the file restore is currently working
249 on. This saves hours when restoring single files from large backups,
250 saves the tapes and the drive's head.
252 Attempt to calculate the amount of tape needed at a particular density.
253 If this amount is exceeded,
255 prompts for a new tape.
256 It is recommended to be a bit conservative on this option.
257 The default tape length is 2300 feet. Specifying the tape size
258 overrides end-of-media detection.
261 Size estimate. Determine the amount of space
262 that is needed to perform the dump without
263 actually doing it, and display the estimated
264 number of bytes it will take. This is useful
265 with incremental dumps to determine how many
266 volumes of media will be needed.
268 Use the specified date as the starting time for the dump
269 instead of the time determined from looking in
273 is the same as that of
275 This option is useful for automated dump scripts that wish to
276 dump over a specific period of time.
279 option is mutually exclusive from the
285 after a successful dump.
288 is readable by people, consisting of one
289 free format record per line:
295 There may be only one entry per filesystem at each level.
298 may be edited to change any of the fields,
302 tells the operator what file systems need to be dumped.
303 This information is gleaned from the files
311 to print out, for all file systems in
313 and regognized file systems in
315 the most recent dump date and level,
316 and highlights those that should be dumped.
319 option is set, all other options are ignored, and
325 but prints only recognized filesystems in
327 which need to be dumped.
328 .It Fl z Ar compression level
329 Compress every block to be written on the tape using zlib library. This
330 option will work only when dumping to a file or pipe or, when dumping
331 to a tape drive, if the tape drive is capable of writing variable
332 length blocks. You will need at least the 0.4b22 version of restore in
333 order to extract compressed tapes. Tapes written using compression will
334 not be compatible with the BSD tape format. The (optional) parameter
335 specifies the compression level zlib will use. The default compression
340 requires operator intervention on these conditions:
345 disk read error (if there is more than a threshold of 32).
346 In addition to alerting all operators implied by the
350 interacts with the operator on
352 control terminal at times when
354 can no longer proceed,
355 or if something is grossly wrong.
360 be answered by typing
366 Since making a dump involves a lot of time and effort for full dumps,
368 checkpoints itself at the start of each tape volume.
369 If writing that volume fails for some reason,
372 with operator permission,
373 restart itself from the checkpoint
374 after the old tape has been rewound and removed,
375 and a new tape has been mounted.
378 tells the operator what is going on at periodic intervals,
379 including usually low estimates of the number of blocks to write,
380 the number of tapes it will take, the time to completion, and
381 the time to the tape change.
382 The output is verbose,
383 so that others know that the terminal
387 and will be for some time.
389 In the event of a catastrophic disk event, the time required
390 to restore all the necessary backup tapes or files to disk
391 can be kept to a minimum by staggering the incremental dumps.
392 An efficient method of staggering incremental dumps
393 to minimize the number of tapes follows:
394 .Bl -bullet -offset indent
396 Always start with a level 0 backup, for example:
397 .Bd -literal -offset indent
398 /sbin/dump -0u -f /dev/st0 /usr/src
401 This should be done at set intervals, say once a month or once every two months,
402 and on a set of fresh tapes that is saved forever.
404 After a level 0, dumps of active file
405 systems are taken on a daily basis,
406 using a modified Tower of Hanoi algorithm,
407 with this sequence of dump levels:
408 .Bd -literal -offset indent
409 3 2 5 4 7 6 9 8 9 9 ...
412 For the daily dumps, it should be possible to use a fixed number of tapes
413 for each day, used on a weekly basis.
414 Each week, a level 1 dump is taken, and
415 the daily Hanoi sequence repeats beginning with 3.
416 For weekly dumps, another fixed set of tapes per dumped file system is
417 used, also on a cyclical basis.
420 After several months or so, the daily and weekly tapes should get
421 rotated out of the dump cycle and fresh tapes brought in.
425 If no -f option was specified,
427 will use the device specified via
435 .Qq user@host:tapename .
437 The environment variable
439 will be used to determine the pathname of the remote
444 uses the contents of this variable to determine the name of the
445 remote shell command to use when doing remote backups (rsh, ssh etc.).
446 If this variable is not set,
448 will be used, but only root will be able to do remote backups.
450 .Bl -tag -width __DUMPDATES__ -compact
452 default tape unit to dump to
456 dump table: file systems and frequency
469 exits with zero status on success.
470 Startup errors are indicated with an exit code of 1;
471 abnormal termination is indicated with an exit code of 3.
473 It might be considered a bug that this version of dump can only handle ext2
474 filesystems. Specifically, it does not work with FAT filesystems.
476 Fewer than 32 read errors on the filesystem are ignored. If noticing
477 read errors is important, the output from dump can be parsed to look for lines
478 that contain the text 'read error'.
480 Each reel requires a new process, so parent processes for
481 reels already written just hang around until the entire tape
486 knew about the dump sequence,
487 kept track of the tapes scribbled on,
488 told the operator which tape to mount when,
489 and provided more assistance
490 for the operator running
494 cannot do remote backups without being run as root, due to its
496 Presently, it works if you set it setuid (like it used to be), but this
497 might constitute a security risk. Note that you can set RSH to use
498 a remote shell program instead.
502 backup suite was ported to Linux's Second Extended File System
503 by Remy Card <card@Linux.EU.Org>. He maintained the initial versions
504 of dump (up and including 0.4b4, released in january 1997).
506 Starting with 0.4b5, the new maintainer is Stelian Pop
512 backup suite is available from
514 http://dump.sourceforge.net