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29 .\" $Id: dump.8.in,v 1.52 2003/03/31 09:42:57 stelian Exp $
31 .TH DUMP 8 "version __VERSION__ of __DATE__" BSD "System management commands"
33 dump \- ext2/3 filesystem backup
36 [\fB\-0123456789ackMnqSuv\fR]
38 [\fB\-B \fIrecords\fR]
39 [\fB\-b \fIblocksize\fR]
40 [\fB\-d \fIdensity\fR]
42 [\fB\-e \fIinode numbers\fR]
47 [\fB\-I \fInr errors\fR]
48 [\fB\-j\fIcompression level\fR]
54 [\fB\-z\fIcompression level\fR]
58 [\fB\-W \fR| \fB\-w\fR]
60 (The 4.3BSD option syntax is implemented for backward compatibility but is not
64 examines files on an ext2/3 filesystem and determines which files need to be
65 backed up. These files are copied to the given disk, tape or other storage
66 medium for safe keeping (see the
68 option below for doing remote backups). A dump that is larger than the output
69 medium is broken into multiple volumes. On most media the size is determined by
70 writing until an end-of-media indication is returned.
72 On media that cannot reliably return an end-of-media indication (such as some
73 cartridge tape drives), each volume is of a fixed size; the actual size is
74 determined by specifying cartridge media, or via the tape size, density and/or
75 block count options below. By default, the same output file name is used for
76 each volume after prompting the operator to change media.
79 is either a mountpoint of a filesystem or a list of files and directories to be
80 backed up as a subset of a filesystem. In the former case, either the path to a
81 mounted filesystem or the device of an unmounted filesystem can be used. In the
82 latter case, certain restrictions are placed on the backup:
84 is not allowed, the only dump level that is supported is
86 and all the files and directories must reside on the same filesystem.
88 The following options are supported by
92 Dump levels. A level 0, full backup, guarantees the entire file system is
93 copied (but see also the
95 option below). A level number above 0, incremental backup, tells
98 copy all files new or modified since the last dump of a lower level. The
102 \*(lqauto-size\*(rq. Bypass all tape length calculations, and write until an
103 end-of-media indication is returned. This works best for most modern tape
104 drives, and is the default. Use of this option is particularly recommended when
105 appending to an existing tape, or using a tape drive with hardware compression
106 (where you can never be sure about the compression ratio).
108 .BI \-A " archive_file"
109 Archive a dump table-of-contents in the specified
113 to determine whether a file is in the dump file that is being restored.
116 The number of kilobytes per dump record. The default blocksize is 10
117 and the maximal value is 1024.
118 Note however that, since the IO system slices all requests into chunks
121 (which can be as low as 64kB), you can experience problems with
125 when using a higher value, depending on your kernel and/or libC versions.
128 The number of 1 kB blocks per volume. Not normally required, as
130 can detect end-of-media. When the specified size is reached,
132 waits for you to change the volume. This option overrides the calculation of
133 tape size based on length and density. If compression is on this limits the
134 size of the compressed output per volume.
137 Change the defaults for use with a cartridge tape drive, with a density of 8000
138 bpi, and a length of 1700 feet. Specifying a cartridge drive overrides the
139 end-of-media detection.
144 The default is 1600BPI. Specifying a tape density overrides the end-of-media
148 Set the path name of the file storing the information about the previous
149 full and incremental dumps. The default location is
157 parameter is a comma separated list of inode numbers (you can use
159 to find the inode number for a file or directory).
162 Read list of inodes to be excluded from the dump from the text file
166 should be an ordinary file containing inode numbers separated by newlines.
172 may be a special device file like
176 (a floppy disk drive), an ordinary file, or
178 (the standard output). Multiple file names may be given as a single argument
179 separated by commas. Each file will be used for one dump volume in the order
180 listed; if the dump requires more volumes than the number of names given,
181 the last file name will used for all remaining volumes after prompting for
182 media changes. If the name of the file is of the form
187 writes to the named file on the remote host using
189 The default path name of the remote
193 this can be overridden by the environment variable
197 Run script at the end of each tape (except for the last one).
198 The device name and the current volume number are passed on the
199 command line. The script must return 0 if
201 should continue without asking the user to change the tape, 1 if
203 should continue but ask the user to change the tape. Any other exit code will
206 to abort. For security reasons,
208 reverts back to the real user ID and the real group ID before running the
216 only for dumps at or above the given
218 The default honor level is 1, so that incremental backups omit such files but
219 full backups retain them.
224 will ignore the first 32 read errors on the file system before asking for
225 operator intervention. You can change this using this flag to any value. This
226 is useful when running
228 on an active filesystem where read errors simply indicate an inconsistency
229 between the mapping and dumping passes.
231 A value of 0 means that all read errors will be ignored.
233 .BI \-j "compression level"
234 Compress every block to be written on the tape using bzlib library. This option
235 will work only when dumping to a file or pipe or, when dumping to a tape drive,
236 if the tape drive is capable of writing variable length blocks. You will need
237 at least the 0.4b24 version of
239 in order to extract compressed tapes. Tapes written using compression will not
240 be compatible with the BSD tape format. The (optional) parameter specifies the
241 compression level bzlib will use. The default compression level is 2. If the
242 optional parameter is specified, there should be no white space between the
243 option letter and the parameter.
246 Use Kerberos authentication to talk to remote tape servers. (Only available if
247 this option was enabled when
252 The user-supplied text string
254 is placed into the dump header, where tools like
258 can access it. Note that this label is limited to be at most
260 (currently 16) characters, which must include the terminating \e0.
263 If this flag is specified,
265 will optimise the output for inodes having been changed but not modified since
266 the last dump ('changed' and 'modified' have the meaning defined in
270 will save only the metadata, instead of saving the entire inode contents.
271 Inodes which are either directories or have been modified since the last dump
272 are saved in a regular way. Uses of this flag must be consistent, meaning that
273 either every dump in an incremental dump set have the flag, or no one has it.
275 Tapes written using such 'metadata only' inodes will not be compatible with the
276 BSD tape format or older versions of
280 Enable the multi-volume feature. The name specified with
282 is treated as a prefix and
284 writes in sequence to
285 .I <prefix>001, <prefix>002
286 etc. This can be useful when dumping to files on an ext2 partition, in order to
287 bypass the 2GB file size limitation.
292 requires operator attention, notify all operators in the group
294 by means similar to a
300 abort immediately whenever operator attention is required, without prompting in
301 case of write errors, tape changes etc.
304 Enable the Quick File Access support. Tape positions for each inode are stored
309 (if called with parameter
311 and the filename) to directly position the tape at the file
313 is currently working on. This saves hours when restoring single files from
314 large backups, saves the tapes and the drive's head.
316 It is recommended to set up the st driver to return logical tape positions
317 rather than physical before calling
321 Since not all tape devices support physical tape positions those tape devices
322 return an error during
324 when the st driver is set to the default physical setting. Please see the
330 man page, on how to set the driver to return logical tape positions.
336 always make sure the st driver is set to return the same type of tape position
337 used during the call to
343 This option can be used when dumping to local tapes (see above) or to local
347 Attempt to calculate the amount of tape needed at a particular density. If this
350 prompts for a new tape. It is recommended to be a bit conservative on this
351 option. The default tape length is 2300 feet. Specifying the tape size
352 overrides end-of-media detection.
355 Size estimate. Determine the amount of space that is needed to perform the dump
356 without actually doing it, and display the estimated number of bytes it will
357 take. This is useful with incremental dumps to determine how many volumes of
358 media will be needed.
361 Use the specified date as the starting time for the dump instead of the time
362 determined from looking in
366 is the same as that of
368 followed by an rfc822 timezone specification: either a plus or minus sign
369 followed by two digits for the number of hours and two digits for the minutes.
370 For example, -0800 for eight hours west of Greenwich or +0230 for two hours
371 and a half east of Greenwich. This timezone offset takes into account
372 daylight savings time (if applicable to the timezone): UTC offsets
373 when daylight savings time is in effect will be different than offsets
374 when daylight savings time is not in effect. For backward
375 compatibility, if no timezone is specified, a local time is assumed.
376 This option is useful for automated dump scripts that wish to dump over a
377 specific period of time. The
379 option is mutually exclusive from the
386 after a successful dump. The format of
388 is readable by people, consisting of one free format record per line:
389 filesystem name, increment level and
391 format dump date followed by a rfc822 timezone specification (see the
393 option for details). If no timezone offset is specified, times are interpreted
394 as local. Whenever the file is written, all dates in the file are converted
395 to the local time zone, without changing the UTC times. There
396 may be only one entry per filesystem at each level. The file
398 may be edited to change any of the fields, if necessary.
405 to print extra information which could be helpful in debug sessions.
409 tells the operator what file systems need to be dumped. This information is
410 gleaned from the files
418 to print out, for all file systems in
420 and regognized file systems in
424 the most recent dump date and level, and highlights those that should be
427 option is set, all other options are ignored, and
434 but prints only recognized filesystems in
438 which need to be dumped.
441 Compress every block to be written to the tape using the lzo library.
442 This doesn't compress as well as the zlib library but it's much faster.
443 This option will work only when dumping to a file or pipe or, when dumping to
444 a tape drive, if the tape drive is capable of writing variable length blocks.
445 You will need at least the 0.4b34 version of
447 in order to extract compressed tapes. Tapes written using compression will not
448 be compatible with the BSD tape format.
450 .BI \-z "compression level"
451 Compress every block to be written on the tape using zlib library. This option
452 will work only when dumping to a file or pipe or, when dumping to a tape drive,
453 if the tape drive is capable of writing variable length blocks. You will need
454 at least the 0.4b22 version of
456 in order to extract compressed tapes. Tapes written using compression will not
457 be compatible with the BSD tape format. The (optional) parameter specifies the
458 compression level zlib will use. The default compression level is 2. If the
459 optional parameter is specified, there should be no white space between the
460 option letter and the parameter.
463 requires operator intervention on these conditions: end of tape, end of dump,
464 tape write error, tape open error or disk read error (if there is more than a
465 threshold of nr errors). In addition to alerting all operators implied by the
469 interacts with the operator on dump's control terminal at times when
471 can no longer proceed, or if something is grossly wrong. All questions
475 be answered by typing \*(lqyes\*(rq or \*(lqno\*(rq, appropriately.
477 Since making a dump involves a lot of time and effort for full dumps,
479 checkpoints itself at the start of each tape volume. If writing that volume
480 fails for some reason,
482 will, with operator permission, restart itself from the checkpoint after the
483 old tape has been rewound and removed, and a new tape has been mounted.
486 tells the operator what is going on at periodic intervals, including usually
487 low estimates of the number of blocks to write, the number of tapes it will
488 take, the time to completion, and the time to the tape change. The output is
489 verbose, so that others know that the terminal controlling
491 is busy, and will be for some time.
493 In the event of a catastrophic disk event, the time required to restore all the
494 necessary backup tapes or files to disk can be kept to a minimum by staggering
495 the incremental dumps. An efficient method of staggering incremental dumps to
496 minimize the number of tapes follows:
498 Always start with a level 0 backup, for example:
500 .B /sbin/dump -0u -f /dev/st0 /usr/src
503 This should be done at set intervals, say once a month or once every two months,
504 and on a set of fresh tapes that is saved forever.
506 After a level 0, dumps of active file systems are taken on a daily basis, using
507 a modified Tower of Hanoi algorithm, with this sequence of dump levels:
509 .B 3 2 5 4 7 6 9 8 9 9 ...
512 For the daily dumps, it should be possible to use a fixed number of tapes for
513 each day, used on a weekly basis. Each week, a level 1 dump is taken, and the
514 daily Hanoi sequence repeats beginning with 3. For weekly dumps, another fixed
515 set of tapes per dumped file system is used, also on a cyclical basis.
517 After several months or so, the daily and weekly tapes should get rotated out
518 of the dump cycle and fresh tapes brought in.
524 option was specified,
526 will use the device specified via
534 .IR user@host:tapename .
537 The environment variable
539 will be used to determine the pathname of the remote
545 uses the contents of this variable to determine the name of the remote shell
546 command to use when doing remote backups (rsh, ssh etc.). If this variable is
549 will be used, but only root will be able to do remote backups.
553 default tape unit to dump to
559 dump table: file systems and frequency
562 dump table: mounted file systems
576 file has changed in release 0.4b34, however, the file will be read
577 correctly with either pre-0.4b34 or 0.4b34 and later versions of
579 provided that the machine on which
581 is run did not change timezones (which should be a fairly rare occurence).
584 exits with zero status on success. Startup errors are indicated with an exit
585 code of 1; abnormal termination is indicated with an exit code of 3.
587 It might be considered a bug that this version of dump can only handle ext2/3
588 filesystems. Specifically, it does not work with FAT filesystems.
590 Fewer than 32 read errors (change this with
592 on the filesystem are ignored. If noticing read errors is important, the output
593 from dump can be parsed to look for lines that contain the text 'read error'.
595 When a read error occurs,
597 prints out the corresponding physical disk block and sector number and the
598 ext2/3 logical block number. It doesn't print out the corresponing file name or
599 even the inode number. The user has to use
607 number printed out by
609 into an inode number, then into a file name.
611 Each reel requires a new process, so parent processes for reels already written
612 just hang around until the entire tape is written.
614 The estimated number of tapes is not correct if compression is on.
618 knew about the dump sequence, kept track of the tapes scribbled on, told the
619 operator which tape to mount when, and provided more assistance for the
624 cannot do remote backups without being run as root, due to its security history.
625 Presently, it works if you set it setuid (like it used to be), but this might
626 constitute a security risk. Note that you can set
628 to use a remote shell program instead.
632 backup suite was ported to Linux's Second Extended File System by Remy Card
633 <card@Linux.EU.Org>. He maintained the initial versions of
635 (up and including 0.4b4, released in january 1997).
637 Starting with 0.4b5, the new maintainer is Stelian Pop <stelian@popies.net>.
641 backup suite is available from <http://dump.sourceforge.net>
646 .B Version 6 AT&T UNIX.