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29 .\" $Id: dump.8.in,v 1.53 2003/05/07 14:45:20 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,
119 option has been used to specify a tape density of 6250BPI or more,
120 in which case the default blocksize is 32. Th maximal value is 1024.
121 Note however that, since the IO system slices all requests into chunks
124 (which can be as low as 64kB), you can experience problems with
128 when using a higher value, depending on your kernel and/or libC versions.
131 The number of 1 kB blocks per volume. Not normally required, as
133 can detect end-of-media. When the specified size is reached,
135 waits for you to change the volume. This option overrides the calculation of
136 tape size based on length and density. If compression is on this limits the
137 size of the compressed output per volume.
140 Change the defaults for use with a cartridge tape drive, with a density of 8000
141 bpi, and a length of 1700 feet. Specifying a cartridge drive overrides the
142 end-of-media detection.
147 The default is 1600BPI. Specifying a tape density overrides the end-of-media
151 Set the path name of the file storing the information about the previous
152 full and incremental dumps. The default location is
160 parameter is a comma separated list of inode numbers (you can use
162 to find the inode number for a file or directory).
165 Read list of inodes to be excluded from the dump from the text file
169 should be an ordinary file containing inode numbers separated by newlines.
175 may be a special device file like
179 (a floppy disk drive), an ordinary file, or
181 (the standard output). Multiple file names may be given as a single argument
182 separated by commas. Each file will be used for one dump volume in the order
183 listed; if the dump requires more volumes than the number of names given,
184 the last file name will used for all remaining volumes after prompting for
185 media changes. If the name of the file is of the form
190 writes to the named file on the remote host using
192 The default path name of the remote
196 this can be overridden by the environment variable
200 Run script at the end of each tape (except for the last one).
201 The device name and the current volume number are passed on the
202 command line. The script must return 0 if
204 should continue without asking the user to change the tape, 1 if
206 should continue but ask the user to change the tape. Any other exit code will
209 to abort. For security reasons,
211 reverts back to the real user ID and the real group ID before running the
219 only for dumps at or above the given
221 The default honor level is 1, so that incremental backups omit such files but
222 full backups retain them.
227 will ignore the first 32 read errors on the file system before asking for
228 operator intervention. You can change this using this flag to any value. This
229 is useful when running
231 on an active filesystem where read errors simply indicate an inconsistency
232 between the mapping and dumping passes.
234 A value of 0 means that all read errors will be ignored.
236 .BI \-j "compression level"
237 Compress every block to be written on the tape using bzlib library. This option
238 will work only when dumping to a file or pipe or, when dumping to a tape drive,
239 if the tape drive is capable of writing variable length blocks. You will need
240 at least the 0.4b24 version of
242 in order to extract compressed tapes. Tapes written using compression will not
243 be compatible with the BSD tape format. The (optional) parameter specifies the
244 compression level bzlib will use. The default compression level is 2. If the
245 optional parameter is specified, there should be no white space between the
246 option letter and the parameter.
249 Use Kerberos authentication to talk to remote tape servers. (Only available if
250 this option was enabled when
255 The user-supplied text string
257 is placed into the dump header, where tools like
261 can access it. Note that this label is limited to be at most
263 (currently 16) characters, which must include the terminating \e0.
266 If this flag is specified,
268 will optimise the output for inodes having been changed but not modified since
269 the last dump ('changed' and 'modified' have the meaning defined in
273 will save only the metadata, instead of saving the entire inode contents.
274 Inodes which are either directories or have been modified since the last dump
275 are saved in a regular way. Uses of this flag must be consistent, meaning that
276 either every dump in an incremental dump set have the flag, or no one has it.
278 Tapes written using such 'metadata only' inodes will not be compatible with the
279 BSD tape format or older versions of
283 Enable the multi-volume feature. The name specified with
285 is treated as a prefix and
287 writes in sequence to
288 .I <prefix>001, <prefix>002
289 etc. This can be useful when dumping to files on an ext2 partition, in order to
290 bypass the 2GB file size limitation.
295 requires operator attention, notify all operators in the group
297 by means similar to a
303 abort immediately whenever operator attention is required, without prompting in
304 case of write errors, tape changes etc.
307 Enable the Quick File Access support. Tape positions for each inode are stored
312 (if called with parameter
314 and the filename) to directly position the tape at the file
316 is currently working on. This saves hours when restoring single files from
317 large backups, saves the tapes and the drive's head.
319 It is recommended to set up the st driver to return logical tape positions
320 rather than physical before calling
324 Since not all tape devices support physical tape positions those tape devices
325 return an error during
327 when the st driver is set to the default physical setting. Please see the
333 man page, on how to set the driver to return logical tape positions.
339 always make sure the st driver is set to return the same type of tape position
340 used during the call to
346 This option can be used when dumping to local tapes (see above) or to local
350 Attempt to calculate the amount of tape needed at a particular density. If this
353 prompts for a new tape. It is recommended to be a bit conservative on this
354 option. The default tape length is 2300 feet. Specifying the tape size
355 overrides end-of-media detection.
358 Size estimate. Determine the amount of space that is needed to perform the dump
359 without actually doing it, and display the estimated number of bytes it will
360 take. This is useful with incremental dumps to determine how many volumes of
361 media will be needed.
364 Use the specified date as the starting time for the dump instead of the time
365 determined from looking in
369 is the same as that of
371 followed by an rfc822 timezone specification: either a plus or minus sign
372 followed by two digits for the number of hours and two digits for the minutes.
373 For example, -0800 for eight hours west of Greenwich or +0230 for two hours
374 and a half east of Greenwich. This timezone offset takes into account
375 daylight savings time (if applicable to the timezone): UTC offsets
376 when daylight savings time is in effect will be different than offsets
377 when daylight savings time is not in effect. For backward
378 compatibility, if no timezone is specified, a local time is assumed.
379 This option is useful for automated dump scripts that wish to dump over a
380 specific period of time. The
382 option is mutually exclusive from the
389 after a successful dump. The format of
391 is readable by people, consisting of one free format record per line:
392 filesystem name, increment level and
394 format dump date followed by a rfc822 timezone specification (see the
396 option for details). If no timezone offset is specified, times are interpreted
397 as local. Whenever the file is written, all dates in the file are converted
398 to the local time zone, without changing the UTC times. There
399 may be only one entry per filesystem at each level. The file
401 may be edited to change any of the fields, if necessary.
408 to print extra information which could be helpful in debug sessions.
412 tells the operator what file systems need to be dumped. This information is
413 gleaned from the files
421 to print out, for all file systems in
423 and regognized file systems in
427 the most recent dump date and level, and highlights those that should be
430 option is set, all other options are ignored, and
437 but prints only recognized filesystems in
441 which need to be dumped.
444 Compress every block to be written to the tape using the lzo library.
445 This doesn't compress as well as the zlib library but it's much faster.
446 This option will work only when dumping to a file or pipe or, when dumping to
447 a tape drive, if the tape drive is capable of writing variable length blocks.
448 You will need at least the 0.4b34 version of
450 in order to extract compressed tapes. Tapes written using compression will not
451 be compatible with the BSD tape format.
453 .BI \-z "compression level"
454 Compress every block to be written on the tape using zlib library. This option
455 will work only when dumping to a file or pipe or, when dumping to a tape drive,
456 if the tape drive is capable of writing variable length blocks. You will need
457 at least the 0.4b22 version of
459 in order to extract compressed tapes. Tapes written using compression will not
460 be compatible with the BSD tape format. The (optional) parameter specifies the
461 compression level zlib will use. The default compression level is 2. If the
462 optional parameter is specified, there should be no white space between the
463 option letter and the parameter.
466 requires operator intervention on these conditions: end of tape, end of dump,
467 tape write error, tape open error or disk read error (if there is more than a
468 threshold of nr errors). In addition to alerting all operators implied by the
472 interacts with the operator on dump's control terminal at times when
474 can no longer proceed, or if something is grossly wrong. All questions
478 be answered by typing \*(lqyes\*(rq or \*(lqno\*(rq, appropriately.
480 Since making a dump involves a lot of time and effort for full dumps,
482 checkpoints itself at the start of each tape volume. If writing that volume
483 fails for some reason,
485 will, with operator permission, restart itself from the checkpoint after the
486 old tape has been rewound and removed, and a new tape has been mounted.
489 tells the operator what is going on at periodic intervals, including usually
490 low estimates of the number of blocks to write, the number of tapes it will
491 take, the time to completion, and the time to the tape change. The output is
492 verbose, so that others know that the terminal controlling
494 is busy, and will be for some time.
496 In the event of a catastrophic disk event, the time required to restore all the
497 necessary backup tapes or files to disk can be kept to a minimum by staggering
498 the incremental dumps. An efficient method of staggering incremental dumps to
499 minimize the number of tapes follows:
501 Always start with a level 0 backup, for example:
503 .B /sbin/dump -0u -f /dev/st0 /usr/src
506 This should be done at set intervals, say once a month or once every two months,
507 and on a set of fresh tapes that is saved forever.
509 After a level 0, dumps of active file systems are taken on a daily basis, using
510 a modified Tower of Hanoi algorithm, with this sequence of dump levels:
512 .B 3 2 5 4 7 6 9 8 9 9 ...
515 For the daily dumps, it should be possible to use a fixed number of tapes for
516 each day, used on a weekly basis. Each week, a level 1 dump is taken, and the
517 daily Hanoi sequence repeats beginning with 3. For weekly dumps, another fixed
518 set of tapes per dumped file system is used, also on a cyclical basis.
520 After several months or so, the daily and weekly tapes should get rotated out
521 of the dump cycle and fresh tapes brought in.
527 option was specified,
529 will use the device specified via
537 .IR user@host:tapename .
540 The environment variable
542 will be used to determine the pathname of the remote
548 uses the contents of this variable to determine the name of the remote shell
549 command to use when doing remote backups (rsh, ssh etc.). If this variable is
552 will be used, but only root will be able to do remote backups.
556 default tape unit to dump to
562 dump table: file systems and frequency
565 dump table: mounted file systems
579 file has changed in release 0.4b34, however, the file will be read
580 correctly with either pre-0.4b34 or 0.4b34 and later versions of
582 provided that the machine on which
584 is run did not change timezones (which should be a fairly rare occurence).
587 exits with zero status on success. Startup errors are indicated with an exit
588 code of 1; abnormal termination is indicated with an exit code of 3.
590 It might be considered a bug that this version of dump can only handle ext2/3
591 filesystems. Specifically, it does not work with FAT filesystems.
593 Fewer than 32 read errors (change this with
595 on the filesystem are ignored. If noticing read errors is important, the output
596 from dump can be parsed to look for lines that contain the text 'read error'.
598 When a read error occurs,
600 prints out the corresponding physical disk block and sector number and the
601 ext2/3 logical block number. It doesn't print out the corresponing file name or
602 even the inode number. The user has to use
610 number printed out by
612 into an inode number, then into a file name.
614 Each reel requires a new process, so parent processes for reels already written
615 just hang around until the entire tape is written.
617 The estimated number of tapes is not correct if compression is on.
621 knew about the dump sequence, kept track of the tapes scribbled on, told the
622 operator which tape to mount when, and provided more assistance for the
627 cannot do remote backups without being run as root, due to its security history.
628 Presently, it works if you set it setuid (like it used to be), but this might
629 constitute a security risk. Note that you can set
631 to use a remote shell program instead.
635 backup suite was ported to Linux's Second Extended File System by Remy Card
636 <card@Linux.EU.Org>. He maintained the initial versions of
638 (up and including 0.4b4, released in january 1997).
640 Starting with 0.4b5, the new maintainer is Stelian Pop <stelian@popies.net>.
644 backup suite is available from <http://dump.sourceforge.net>
649 .B Version 6 AT&T UNIX.