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33 .\" $Id: dump.8.in,v 1.42 2002/06/10 14:05:00 stelian Exp $
37 .Os "dump __VERSION__"
40 .Nd ext2 filesystem backup
43 .Op Fl 0123456789ackMnqSuv
48 .Op Fl e Ar inode numbers
54 .Op Fl j Ar compression level
59 .Op Fl z Ar compression level
67 option syntax is implemented for backward compatibility but
68 is not documented here.)
73 and determines which files
74 need to be backed up. These files
75 are copied to the given disk, tape or other
76 storage medium for safe keeping (see the
78 option below for doing remote backups).
79 A dump that is larger than the output medium is broken into
81 On most media the size is determined by writing until an
82 end-of-media indication is returned.
84 On media that cannot reliably return an end-of-media indication
85 (such as some cartridge tape drives), each volume is of a fixed size;
86 the actual size is determined by specifying cartridge media, or via the
87 tape size, density and/or block count options below.
88 By default, the same output file name is used for each volume
89 after prompting the operator to change media.
92 is either a mountpoint of a filesystem
93 or a list of files and directories to be backed up as a subset of a
95 In the former case, either the path to a mounted filesystem
96 or the device of an unmounted filesystem can be used.
97 In the latter case, certain restrictions are placed on the backup:
99 is not allowed, the only dump level that is supported is
101 and all the files and directories must reside on the same filesystem.
103 The following options are supported by
108 A level 0, full backup,
109 guarantees the entire file system is copied
113 A level number above 0,
118 copy all files new or modified since the
119 last dump of a lower level.
120 The default level is 9.
123 Bypass all tape length calculations, and write
124 until an end-of-media indication is returned. This works best
125 for most modern tape drives, and is the default.
126 Use of this option is particularly recommended when appending to an
127 existing tape, or using a tape drive with hardware compression
128 (where you can never be sure about the compression ratio).
129 .It Fl A Ar archive_file
130 Archive a dump table-of-contents in the
135 to determine whether a file is in the dump file that is being restored.
136 .It Fl b Ar blocksize
137 The number of kilobytes per dump record.
138 Since the IO system slices all requests into chunks of MAXBSIZE
139 (typically 64kB), it is not possible to use a larger blocksize
140 without having problems later with
144 will constrain writes to MAXBSIZE.
145 The default blocksize is 10.
147 The number of 1 kB blocks per volume. Not normally required, as
149 can detect end-of-media. When the specified size is reached,
151 waits for you to change the volume. This option overrides
152 the calculation of tape size based on length and density.
153 If compression is on this limits the size of the compressed
156 Change the defaults for use with a cartridge tape drive, with a density
157 of 8000 bpi, and a length of 1700 feet. Specifying a cartridge drive
158 overrides the end-of-media detection.
162 The default is 1600BPI. Specifying a tape density overrides the
163 end-of-media detection.
169 parameter is a comma separated list of inode numbers (you can use
171 to find the inode number for a file or directory).
173 Read list of inodes to be excluded from the dump from the text file
177 should be an ordinary file containing inode numbers separated by
183 may be a special device file
188 (a floppy disk drive),
192 (the standard output).
193 Multiple file names may be given as a single argument separated by commas.
194 Each file will be used for one dump volume in the order listed;
195 if the dump requires more volumes than the number of names given,
196 the last file name will used for all remaining volumes after prompting
198 If the name of the file is of the form
203 writes to the named file on the remote host using
205 The default path name of the remote
208 .\" rmt path, is the path on the remote host
210 this can be overridden by the environment variable
213 Run script at the end of each tape. The device name and the
214 current volume number are passed on the command line.
215 The script must return 0 if
217 should continue without asking the user to change the tape, 1 if
219 should continue but ask the user to change the tape.
220 Any other exit code will cause
223 For security reasons,
225 reverts back to the real user ID and the real group ID before
232 only for dumps at or above the given
234 The default honor level is 1,
235 so that incremental backups omit such files
236 but full backups retain them.
237 .It Fl I Ar nr errors
240 will ignore the first 32 read errors on the file
241 system before asking for operator intervention. You can change this
242 using this flag to any value. This is useful when running
244 on an active filesystem where read errors simply indicate an
245 inconsistency between the mapping and dumping passes.
246 .It Fl j Ar compression level
247 Compress every block to be written on the tape using bzlib library. This
248 option will work only when dumping to a file or pipe or, when dumping
249 to a tape drive, if the tape drive is capable of writing variable
250 length blocks. You will need at least the 0.4b24 version of restore in
251 order to extract compressed tapes. Tapes written using compression will
252 not be compatible with the BSD tape format. The (optional) parameter
253 specifies the compression level bzlib will use. The default compression
254 level is 2. If the optional parameter is specified, there should be no
255 white space between the option letter and the parameter.
257 Use Kerberos authentication to talk to remote tape servers. (Only
258 available if this option was enabled when
262 The user-supplied text string
264 is placed into the dump header, where tools like
269 Note that this label is limited
270 to be at most LBLSIZE (currently 16) characters, which must include
274 If this flag is specified,
276 will optimise the output for inodes having been changed but not
277 modified since the last dump ('changed' and 'modified' have the
278 meaning defined in stat(2)). For those inodes,
280 will save only the metadata, instead of saving the entire inode
281 contents. Inodes which are either directories or have been modified
282 since the last dump are saved in a regular way.
283 Uses of this flag must be consistent, meaning that either every dump
284 in an incremental dump set have the flag, or no one has it.
286 Tapes written using such 'metadata only' inodes will not be compatible
287 with the BSD tape format or older versions of
290 Enable the multi-volume feature. The name specified with
292 is treated as a prefix and
294 writes in sequence to <prefix>001, <prefix>002 etc. This can be
295 useful when dumping to files on an ext2 partition, in order to bypass
296 the 2GB file size limitation.
300 requires operator attention,
301 notify all operators in the group
303 by means similar to a
308 abort immediately whenever operator attention is required,
309 without prompting in case of write errors, tape changes etc.
311 Enable the Quick File Access support. Tape positions for each
312 inode are stored into the file
314 which is used by restore (if called with parameter Q and the filename)
315 to directly position the tape at the file restore is currently working
316 on. This saves hours when restoring single files from large backups,
317 saves the tapes and the drive's head.
319 It is recommended to set up the st driver to return logical tape
320 positions rather than physical before calling dump/restore with
321 parameter Q. Since not all tape devices support physical tape
322 positions those tape devices return an error during dump/restore when
323 the st driver is set to the default physical setting.
324 Please see the st man page, option MTSETDRVBUFFER, or the mt man
325 page, on how to set the driver to return logical tape positions.
327 Before calling restore with parameter Q, always make sure the st
328 driver is set to return the same type of tape position used during the
329 call to dump. Otherwise restore may be confused.
331 This option can be used when dumping to local tapes (see above)
334 Attempt to calculate the amount of tape needed at a particular density.
335 If this amount is exceeded,
337 prompts for a new tape.
338 It is recommended to be a bit conservative on this option.
339 The default tape length is 2300 feet. Specifying the tape size
340 overrides end-of-media detection.
343 Size estimate. Determine the amount of space
344 that is needed to perform the dump without
345 actually doing it, and display the estimated
346 number of bytes it will take. This is useful
347 with incremental dumps to determine how many
348 volumes of media will be needed.
350 Use the specified date as the starting time for the dump
351 instead of the time determined from looking in
355 is the same as that of
357 This option is useful for automated dump scripts that wish to
358 dump over a specific period of time.
361 option is mutually exclusive from the
367 after a successful dump.
370 is readable by people, consisting of one
371 free format record per line:
377 There may be only one entry per filesystem at each level.
380 may be edited to change any of the fields,
387 to print extra information which could be helpful in debug sessions.
390 tells the operator what file systems need to be dumped.
391 This information is gleaned from the files
399 to print out, for all file systems in
401 and regognized file systems in
403 the most recent dump date and level,
404 and highlights those that should be dumped.
407 option is set, all other options are ignored, and
413 but prints only recognized filesystems in
415 which need to be dumped.
416 .It Fl z Ar compression level
417 Compress every block to be written on the tape using zlib library. This
418 option will work only when dumping to a file or pipe or, when dumping
419 to a tape drive, if the tape drive is capable of writing variable
420 length blocks. You will need at least the 0.4b22 version of restore in
421 order to extract compressed tapes. Tapes written using compression will
422 not be compatible with the BSD tape format. The (optional) parameter
423 specifies the compression level zlib will use. The default compression
424 level is 2. If the optional parameter is specified, there should be no
425 white space between the option letter and the parameter.
429 requires operator intervention on these conditions:
434 disk read error (if there is more than a threshold of nr errors).
435 In addition to alerting all operators implied by the
439 interacts with the operator on
441 control terminal at times when
443 can no longer proceed,
444 or if something is grossly wrong.
449 be answered by typing
455 Since making a dump involves a lot of time and effort for full dumps,
457 checkpoints itself at the start of each tape volume.
458 If writing that volume fails for some reason,
461 with operator permission,
462 restart itself from the checkpoint
463 after the old tape has been rewound and removed,
464 and a new tape has been mounted.
467 tells the operator what is going on at periodic intervals,
468 including usually low estimates of the number of blocks to write,
469 the number of tapes it will take, the time to completion, and
470 the time to the tape change.
471 The output is verbose,
472 so that others know that the terminal
476 and will be for some time.
478 In the event of a catastrophic disk event, the time required
479 to restore all the necessary backup tapes or files to disk
480 can be kept to a minimum by staggering the incremental dumps.
481 An efficient method of staggering incremental dumps
482 to minimize the number of tapes follows:
483 .Bl -bullet -offset indent
485 Always start with a level 0 backup, for example:
486 .Bd -literal -offset indent
487 /sbin/dump -0u -f /dev/st0 /usr/src
490 This should be done at set intervals, say once a month or once every two months,
491 and on a set of fresh tapes that is saved forever.
493 After a level 0, dumps of active file
494 systems are taken on a daily basis,
495 using a modified Tower of Hanoi algorithm,
496 with this sequence of dump levels:
497 .Bd -literal -offset indent
498 3 2 5 4 7 6 9 8 9 9 ...
501 For the daily dumps, it should be possible to use a fixed number of tapes
502 for each day, used on a weekly basis.
503 Each week, a level 1 dump is taken, and
504 the daily Hanoi sequence repeats beginning with 3.
505 For weekly dumps, another fixed set of tapes per dumped file system is
506 used, also on a cyclical basis.
509 After several months or so, the daily and weekly tapes should get
510 rotated out of the dump cycle and fresh tapes brought in.
514 If no -f option was specified,
516 will use the device specified via
524 .Qq user@host:tapename .
526 The environment variable
528 will be used to determine the pathname of the remote
533 uses the contents of this variable to determine the name of the
534 remote shell command to use when doing remote backups (rsh, ssh etc.).
535 If this variable is not set,
537 will be used, but only root will be able to do remote backups.
540 .Bl -tag -width __DUMPDATES__ -compact
542 default tape unit to dump to
546 dump table: file systems and frequency
559 exits with zero status on success.
560 Startup errors are indicated with an exit code of 1;
561 abnormal termination is indicated with an exit code of 3.
563 It might be considered a bug that this version of dump can only handle ext2
564 filesystems. Specifically, it does not work with FAT filesystems.
566 Fewer than 32 read errors (change this with -I)
567 on the filesystem are ignored. If noticing
568 read errors is important, the output from dump can be parsed to look for lines
569 that contain the text 'read error'.
571 When a read error occurs,
573 prints out the corresponding physical disk block and sector number and the
574 ext2 logical block number.
575 It doesn't print out the corresponing file name or even the inode number.
584 number printed out by dump into an inode number, then into a file name.
586 Each reel requires a new process, so parent processes for
587 reels already written just hang around until the entire tape
590 The estimated number of tapes is not correct if compression is on.
594 knew about the dump sequence,
595 kept track of the tapes scribbled on,
596 told the operator which tape to mount when,
597 and provided more assistance
598 for the operator running
602 cannot do remote backups without being run as root, due to its
604 Presently, it works if you set it setuid (like it used to be), but this
605 might constitute a security risk. Note that you can set RSH to use
606 a remote shell program instead.
610 backup suite was ported to Linux's Second Extended File System
611 by Remy Card <card@Linux.EU.Org>. He maintained the initial versions
612 of dump (up and including 0.4b4, released in january 1997).
614 Starting with 0.4b5, the new maintainer is Stelian Pop
616 <stelian@popies.net>.
620 backup suite is available from
622 http://dump.sourceforge.net