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29 .\" $Id: dump.8.in,v 1.57 2004/07/13 08:17:32 stelian Exp $
31 .TH DUMP 8 "version __VERSION__ of __DATE__" BSD "System management commands"
33 dump \- ext2/3 filesystem backup
39 [\fB\-B \fIrecords\fR]
40 [\fB\-b \fIblocksize\fR]
41 [\fB\-d \fIdensity\fR]
43 [\fB\-e \fIinode numbers\fR]
48 [\fB\-I \fInr errors\fR]
49 [\fB\-j\fIcompression level\fR]
55 [\fB\-z\fIcompression level\fR]
59 [\fB\-W \fR| \fB\-w\fR]
62 examines files on an ext2/3 filesystem and determines which files need to be
63 backed up. These files are copied to the given disk, tape or other storage
64 medium for safe keeping (see the
66 option below for doing remote backups). A dump that is larger than the output
67 medium is broken into multiple volumes. On most media the size is determined by
68 writing until an end-of-media indication is returned.
70 On media that cannot reliably return an end-of-media indication (such as some
71 cartridge tape drives), each volume is of a fixed size; the actual size is
72 determined by specifying cartridge media, or via the tape size, density and/or
73 block count options below. By default, the same output file name is used for
74 each volume after prompting the operator to change media.
77 is either a mountpoint of a filesystem or a list of files and directories to be
78 backed up as a subset of a filesystem. In the former case, either the path to a
79 mounted filesystem or the device of an unmounted filesystem can be used. In the
80 latter case, certain restrictions are placed on the backup:
82 is not allowed, the only dump level that is supported is
84 and all the files and directories must reside on the same filesystem.
86 The following options are supported by
90 The dump level (any integer). A level 0, full backup, guarantees the
91 entire file system is copied (but see also the
93 option below). A level number above 0, incremental backup, tells
96 copy all files new or modified since the last dump of a lower level. The
97 default level is 9. Historically only levels 0 to 9 were usable in
98 dump, this version is able to understand any integer as a dump level.
101 \*(lqauto-size\*(rq. Bypass all tape length calculations, and write until an
102 end-of-media indication is returned. This works best for most modern tape
103 drives, and is the default. Use of this option is particularly recommended when
104 appending to an existing tape, or using a tape drive with hardware compression
105 (where you can never be sure about the compression ratio).
107 .BI \-A " archive_file"
108 Archive a dump table-of-contents in the specified
112 to determine whether a file is in the dump file that is being restored.
115 The number of kilobytes per dump record. The default blocksize is 10,
118 option has been used to specify a tape density of 6250BPI or more,
119 in which case the default blocksize is 32. Th maximal value is 1024.
120 Note however that, since the IO system slices all requests into chunks
123 (which can be as low as 64kB), you can experience problems with
127 when using a higher value, depending on your kernel and/or libC versions.
130 The number of 1 kB blocks per volume. Not normally required, as
132 can detect end-of-media. When the specified size is reached,
134 waits for you to change the volume. This option overrides the calculation of
135 tape size based on length and density. If compression is on this limits the
136 size of the compressed output per volume. Multiple values may be given
137 as a single argument separated by commas. Each value will be used for one
138 dump volume in the order listed; if
140 creates more volumes than the
141 number of values given, the last value will be used for the remaining
142 volumes. This is useful for filling up already partially filled media
143 (and then continuing with full size volumes on empty media) or mixing media
147 Change the defaults for use with a cartridge tape drive, with a density of 8000
148 bpi, and a length of 1700 feet. Specifying a cartridge drive overrides the
149 end-of-media detection.
154 The default is 1600BPI. Specifying a tape density overrides the end-of-media
158 Set the path name of the file storing the information about the previous
159 full and incremental dumps. The default location is
167 parameter is a comma separated list of inode numbers (you can use
169 to find the inode number for a file or directory).
172 Read list of inodes to be excluded from the dump from the text file
176 should be an ordinary file containing inode numbers separated by newlines.
182 may be a special device file like
186 (a floppy disk drive), an ordinary file, or
188 (the standard output). Multiple file names may be given as a single argument
189 separated by commas. Each file will be used for one dump volume in the order
190 listed; if the dump requires more volumes than the number of names given,
191 the last file name will used for all remaining volumes after prompting for
192 media changes. If the name of the file is of the form
197 writes to the named file on the remote host (which should already
198 exist, dump doesn't create a new remote file) using
200 The default path name of the remote
204 this can be overridden by the environment variable
208 Run script at the end of each tape (except for the last one).
209 The device name and the current volume number are passed on the
210 command line. The script must return 0 if
212 should continue without asking the user to change the tape, 1 if
214 should continue but ask the user to change the tape. Any other exit code will
217 to abort. For security reasons,
219 reverts back to the real user ID and the real group ID before running the
227 only for dumps at or above the given
229 The default honor level is 1, so that incremental backups omit such files but
230 full backups retain them.
235 will ignore the first 32 read errors on the file system before asking for
236 operator intervention. You can change this using this flag to any value. This
237 is useful when running
239 on an active filesystem where read errors simply indicate an inconsistency
240 between the mapping and dumping passes.
242 A value of 0 means that all read errors will be ignored.
244 .BI \-j "compression level"
245 Compress every block to be written on the tape using bzlib library. This option
246 will work only when dumping to a file or pipe or, when dumping to a tape drive,
247 if the tape drive is capable of writing variable length blocks. You will need
248 at least the 0.4b24 version of
250 in order to extract compressed tapes. Tapes written using compression will not
251 be compatible with the BSD tape format. The (optional) parameter specifies the
252 compression level bzlib will use. The default compression level is 2. If the
253 optional parameter is specified, there should be no white space between the
254 option letter and the parameter.
257 Use Kerberos authentication to talk to remote tape servers. (Only available if
258 this option was enabled when
263 The user-supplied text string
265 is placed into the dump header, where tools like
269 can access it. Note that this label is limited to be at most
271 (currently 16) characters, which must include the terminating \e0.
274 If this flag is specified,
276 will optimise the output for inodes having been changed but not modified since
277 the last dump ('changed' and 'modified' have the meaning defined in
281 will save only the metadata, instead of saving the entire inode contents.
282 Inodes which are either directories or have been modified since the last dump
283 are saved in a regular way. Uses of this flag must be consistent, meaning that
284 either every dump 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 with the
287 BSD tape format or older versions of
291 Enable the multi-volume feature. The name specified with
293 is treated as a prefix and
295 writes in sequence to
296 .I <prefix>001, <prefix>002
297 etc. This can be useful when dumping to files on an ext2 partition, in order to
298 bypass the 2GB file size limitation.
303 requires operator attention, notify all operators in the group
305 by means similar to a
311 abort immediately whenever operator attention is required, without prompting in
312 case of write errors, tape changes etc.
315 Enable the Quick File Access support. Tape positions for each inode are stored
320 (if called with parameter
322 and the filename) to directly position the tape at the file
324 is currently working on. This saves hours when restoring single files from
325 large backups, saves the tapes and the drive's head.
327 It is recommended to set up the st driver to return logical tape positions
328 rather than physical before calling
332 Since not all tape devices support physical tape positions those tape devices
333 return an error during
335 when the st driver is set to the default physical setting. Please see the
341 man page, on how to set the driver to return logical tape positions.
347 always make sure the st driver is set to return the same type of tape position
348 used during the call to
354 This option can be used when dumping to local tapes (see above) or to local
358 Attempt to calculate the amount of tape needed at a particular density. If this
361 prompts for a new tape. It is recommended to be a bit conservative on this
362 option. The default tape length is 2300 feet. Specifying the tape size
363 overrides end-of-media detection.
366 Size estimate. Determine the amount of space that is needed to perform the dump
367 without actually doing it, and display the estimated number of bytes it will
368 take. This is useful with incremental dumps to determine how many volumes of
369 media will be needed.
372 Use the specified date as the starting time for the dump instead of the time
373 determined from looking in
377 is the same as that of
379 followed by an rfc822 timezone specification: either a plus or minus sign
380 followed by two digits for the number of hours and two digits for the minutes.
381 For example, -0800 for eight hours west of Greenwich or +0230 for two hours
382 and a half east of Greenwich. This timezone offset takes into account
383 daylight savings time (if applicable to the timezone): UTC offsets
384 when daylight savings time is in effect will be different than offsets
385 when daylight savings time is not in effect. For backward
386 compatibility, if no timezone is specified, a local time is assumed.
387 This option is useful for automated dump scripts that wish to dump over a
388 specific period of time. The
390 option is mutually exclusive from the
397 after a successful dump. The format of
399 is readable by people, consisting of one free format record per line:
400 filesystem name, increment level and
402 format dump date followed by a rfc822 timezone specification (see the
404 option for details). If no timezone offset is specified, times are interpreted
405 as local. Whenever the file is written, all dates in the file are converted
406 to the local time zone, without changing the UTC times. There
407 may be only one entry per filesystem at each level. The file
409 may be edited to change any of the fields, if necessary.
416 to print extra information which could be helpful in debug sessions.
420 tells the operator what file systems need to be dumped. This information is
421 gleaned from the files
429 to print out, for all file systems in
431 and regognized file systems in
435 the most recent dump date and level, and highlights those that should be
438 option is set, all other options are ignored, and
445 but prints only recognized filesystems in
449 which need to be dumped.
452 Compress every block to be written to the tape using the lzo library.
453 This doesn't compress as well as the zlib library but it's much faster.
454 This option will work only when dumping to a file or pipe or, when dumping to
455 a tape drive, if the tape drive is capable of writing variable length blocks.
456 You will need at least the 0.4b34 version of
458 in order to extract compressed tapes. Tapes written using compression will not
459 be compatible with the BSD tape format.
461 .BI \-z "compression level"
462 Compress every block to be written on the tape using zlib library. This option
463 will work only when dumping to a file or pipe or, when dumping to a tape drive,
464 if the tape drive is capable of writing variable length blocks. You will need
465 at least the 0.4b22 version of
467 in order to extract compressed tapes. Tapes written using compression will not
468 be compatible with the BSD tape format. The (optional) parameter specifies the
469 compression level zlib will use. The default compression level is 2. If the
470 optional parameter is specified, there should be no white space between the
471 option letter and the parameter.
474 requires operator intervention on these conditions: end of tape, end of dump,
475 tape write error, tape open error or disk read error (if there is more than a
476 threshold of nr errors). In addition to alerting all operators implied by the
480 interacts with the operator on dump's control terminal at times when
482 can no longer proceed, or if something is grossly wrong. All questions
486 be answered by typing \*(lqyes\*(rq or \*(lqno\*(rq, appropriately.
488 Since making a dump involves a lot of time and effort for full dumps,
490 checkpoints itself at the start of each tape volume. If writing that volume
491 fails for some reason,
493 will, with operator permission, restart itself from the checkpoint after the
494 old tape has been rewound and removed, and a new tape has been mounted.
497 tells the operator what is going on at periodic intervals, including usually
498 low estimates of the number of blocks to write, the number of tapes it will
499 take, the time to completion, and the time to the tape change. The output is
500 verbose, so that others know that the terminal controlling
502 is busy, and will be for some time.
504 In the event of a catastrophic disk event, the time required to restore all the
505 necessary backup tapes or files to disk can be kept to a minimum by staggering
506 the incremental dumps. An efficient method of staggering incremental dumps to
507 minimize the number of tapes follows:
509 Always start with a level 0 backup, for example:
511 .B /sbin/dump -0u -f /dev/st0 /usr/src
514 This should be done at set intervals, say once a month or once every two months,
515 and on a set of fresh tapes that is saved forever.
517 After a level 0, dumps of active file systems are taken on a daily basis, using
518 a modified Tower of Hanoi algorithm, with this sequence of dump levels:
520 .B 3 2 5 4 7 6 9 8 9 9 ...
523 For the daily dumps, it should be possible to use a fixed number of tapes for
524 each day, used on a weekly basis. Each week, a level 1 dump is taken, and the
525 daily Hanoi sequence repeats beginning with 3. For weekly dumps, another fixed
526 set of tapes per dumped file system is used, also on a cyclical basis.
528 After several months or so, the daily and weekly tapes should get rotated out
529 of the dump cycle and fresh tapes brought in.
531 (The 4.3BSD option syntax is implemented for backward compatibility but is not
538 option was specified,
540 will use the device specified via
548 .IR user@host:tapename .
551 The environment variable
553 will be used to determine the pathname of the remote
559 uses the contents of this variable to determine the name of the remote shell
560 command to use when doing remote backups (rsh, ssh etc.). If this variable is
563 will be used, but only root will be able to do remote backups.
567 default tape unit to dump to
573 dump table: file systems and frequency
576 dump table: mounted file systems
590 file has changed in release 0.4b34, however, the file will be read
591 correctly with either pre-0.4b34 or 0.4b34 and later versions of
593 provided that the machine on which
595 is run did not change timezones (which should be a fairly rare occurence).
598 exits with zero status on success. Startup errors are indicated with an exit
599 code of 1; abnormal termination is indicated with an exit code of 3.
601 It might be considered a bug that this version of dump can only handle ext2/3
602 filesystems. Specifically, it does not work with FAT filesystems.
604 Fewer than 32 read errors (change this with
606 on the filesystem are ignored. If noticing read errors is important, the output
607 from dump can be parsed to look for lines that contain the text 'read error'.
609 When a read error occurs,
611 prints out the corresponding physical disk block and sector number and the
612 ext2/3 logical block number. It doesn't print out the corresponing file name or
613 even the inode number. The user has to use
621 number printed out by
623 into an inode number, then into a file name.
625 Each reel requires a new process, so parent processes for reels already written
626 just hang around until the entire tape is written.
628 The estimated number of tapes is not correct if compression is on.
632 knew about the dump sequence, kept track of the tapes scribbled on, told the
633 operator which tape to mount when, and provided more assistance for the
638 cannot do remote backups without being run as root, due to its security history.
639 Presently, it works if you set it setuid (like it used to be), but this might
640 constitute a security risk. Note that you can set
642 to use a remote shell program instead.
646 backup suite was ported to Linux's Second Extended File System by Remy Card
647 <card@Linux.EU.Org>. He maintained the initial versions of
649 (up and including 0.4b4, released in january 1997).
651 Starting with 0.4b5, the new maintainer is Stelian Pop <stelian@popies.net>.
655 backup suite is available from <http://dump.sourceforge.net>
660 .B Version 6 AT&T UNIX.