1.\" Copyright (c) 1980, 1991, 1993 2.\" Regents of the University of California. 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 4. Neither the name of the University nor the names of its contributors 14.\" may be used to endorse or promote products derived from this software 15.\" without specific prior written permission. 16.\" 17.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27.\" SUCH DAMAGE. 28.\" 29.\" @(#)dump.8 8.3 (Berkeley) 5/1/95 30.\" $FreeBSD$ 31.\" 32.Dd February 24, 2006 33.Dt DUMP 8 34.Os 35.Sh NAME 36.Nm dump , 37.Nm rdump 38.Nd file system backup 39.Sh SYNOPSIS 40.Nm 41.Op Fl 0123456789acLnrRSu 42.Op Fl B Ar records 43.Op Fl b Ar blocksize 44.Op Fl C Ar cachesize 45.Op Fl D Ar dumpdates 46.Op Fl d Ar density 47.Op Fl f Ar file | Fl P Ar pipecommand 48.Op Fl h Ar level 49.Op Fl s Ar feet 50.Op Fl T Ar date 51.Ar filesystem 52.Nm 53.Fl W | Fl w 54.Pp 55.Nm rdump 56is an alternate name for 57.Nm . 58.Pp 59.in \" XXX 60(The 61.Bx 4.3 62option syntax is implemented for backward compatibility, but 63is not documented here.) 64.Sh DESCRIPTION 65The 66.Nm 67utility examines files 68on a file system 69and determines which files 70need to be backed up. 71These files 72are copied to the given disk, tape or other 73storage medium for safe keeping (see the 74.Fl f 75option below for doing remote backups). 76A dump that is larger than the output medium is broken into 77multiple volumes. 78On most media the size is determined by writing until an 79end-of-media indication is returned. 80This can be enforced 81by using the 82.Fl a 83option. 84.Pp 85On media that cannot reliably return an end-of-media indication 86(such as some cartridge tape drives) 87each volume is of a fixed size; 88the actual size is determined by the tape size and density and/or 89.Fl B 90options. 91By default, the same output file name is used for each volume 92after prompting the operator to change media. 93.Pp 94The file system to be dumped is specified by the argument 95.Ar filesystem 96as either its device-special file or its mount point 97(if that is in a standard entry in 98.Pa /etc/fstab ) . 99.Pp 100The following options are supported by 101.Nm : 102.Bl -tag -width Ds 103.It Fl 0-9 104Dump levels. 105A level 0, full backup, 106guarantees the entire file system is copied 107(but see also the 108.Fl h 109option below). 110A level number above 0, 111incremental backup, 112tells dump to 113copy all files new or modified since the 114last dump of any lower level. 115The default level is 0. 116.It Fl a 117.Dq auto-size . 118Bypass all tape length considerations, and enforce writing 119until an end-of-media indication is returned. 120This fits best for most modern tape drives. 121Use of this option is particularly 122recommended when appending to an existing tape, or using a tape 123drive with hardware compression (where you can never be sure about 124the compression ratio). 125.It Fl B Ar records 126The number of kilobytes per output volume, except that if it is 127not an integer multiple of the output block size, 128the command uses the next smaller such multiple. 129This option overrides the calculation of tape size 130based on length and density. 131.It Fl b Ar blocksize 132The number of kilobytes per output block. 133The default block size is 10. 134.It Fl C Ar cachesize 135Specify the cache size in megabytes. 136This will greatly improve performance 137at the cost of 138.Nm 139possibly not noticing changes in the file system between passes. 140It is 141recommended that you always use this option when dumping a snapshot. 142Beware that 143.Nm 144forks, and the actual memory use may be larger than the specified cache 145size. 146The recommended cache size is between 8 and 32 (megabytes). 147.It Fl c 148Change the defaults for use with a cartridge tape drive, with a density 149of 8000 bpi, and a length of 1700 feet. 150.It Fl D Ar dumpdates 151Specify an alternate path to the 152.Pa dumpdates 153file. 154The default is 155.Pa /etc/dumpdates . 156.It Fl d Ar density 157Set tape density to 158.Ar density . 159The default is 1600BPI. 160.It Fl f Ar file 161Write the backup to 162.Ar file ; 163.Ar file 164may be a special device file 165like 166.Pa /dev/sa0 167(a tape drive), 168.Pa /dev/fd1 169(a floppy disk drive), 170an ordinary file, 171or 172.Sq Fl 173(the standard output). 174Multiple file names may be given as a single argument separated by commas. 175Each file will be used for one dump volume in the order listed; 176if the dump requires more volumes than the number of names given, 177the last file name will used for all remaining volumes after prompting 178for media changes. 179If the name of the file is of the form 180.Dq host:file , 181or 182.Dq user@host:file , 183.Nm 184writes to the named file on the remote host using 185.Xr rmt 8 . 186The default path name of the remote 187.Xr rmt 8 188program is 189.\" rmt path, is the path on the remote host 190.Pa /etc/rmt ; 191this can be overridden by the environment variable 192.Ev RMT . 193.It Fl P Ar pipecommand 194Use 195.Xr popen 3 196to execute the 197.Xr sh 1 198script string defined by 199.Ar pipecommand 200for the output device of each volume. 201This child pipeline's 202.Dv stdin 203.Pq Pa /dev/fd/0 204is redirected from the 205.Nm 206output stream, and the environment variable 207.Ev DUMP_VOLUME 208is set to the current volume number being written. 209After every volume, the writer side of the pipe is closed and 210.Ar pipecommand 211is executed again. 212Subject to the media size specified by 213.Fl B , 214each volume is written in this manner as if the output were a tape drive. 215.It Fl h Ar level 216Honor the user 217.Dq nodump 218flag 219.Pq Dv UF_NODUMP 220only for dumps at or above the given 221.Ar level . 222The default honor level is 1, 223so that incremental backups omit such files 224but full backups retain them. 225.It Fl L 226This option is to notify 227.Nm 228that it is dumping a live file system. 229To obtain a consistent dump image, 230.Nm 231takes a snapshot of the file system in the 232.Pa .snap 233directory in the root of the file system being dumped and 234then does a dump of the snapshot. 235The snapshot is unlinked as soon as the dump starts, and 236is thus removed when the dump is complete. 237This option is ignored for unmounted or read-only file systems. 238If the 239.Pa .snap 240directory does not exist in the root of the file system being dumped, 241a warning will be issued and the 242.Nm 243will revert to the standard behavior. 244This problem can be corrected by creating a 245.Pa .snap 246directory in the root of the file system to be dumped; 247its owner should be 248.Dq Li root , 249its group should be 250.Dq Li operator , 251and its mode should be 252.Dq Li 0770 . 253.It Fl n 254Whenever 255.Nm 256requires operator attention, 257notify all operators in the group 258.Dq operator 259by means similar to a 260.Xr wall 1 . 261.It Fl r 262Be rsync-friendly. 263Normally dump stores the date of the current 264and prior dump in numerous places throughout the dump. 265These scattered changes significantly slow down rsync or 266another incremental file transfer program when they are 267used to update a remote copy of a level 0 dump, 268since the date changes for each dump. 269This option sets both dates to the epoch, permitting 270rsync to be much more efficient when transferring a dump file. 271.It Fl R 272Be even more rsync-friendly. 273This option disables the storage of the actual inode access time 274(storing it instead as the inode's modified time). 275This option permits rsync to be even more efficient 276when transferring dumps generated from filesystems with numerous files 277which are not changing other than their access times. 278The 279.Fl R 280option also sets 281.Fl r . 282.It Fl S 283Display an estimate of the backup size and the number of 284tapes required, and exit without actually performing the dump. 285.It Fl s Ar feet 286Attempt to calculate the amount of tape needed 287at a particular density. 288If this amount is exceeded, 289.Nm 290prompts for a new tape. 291It is recommended to be a bit conservative on this option. 292The default tape length is 2300 feet. 293.It Fl T Ar date 294Use the specified date as the starting time for the dump 295instead of the time determined from looking in 296the 297.Pa dumpdates 298file. 299The format of date is the same as that of 300.Xr ctime 3 . 301This option is useful for automated dump scripts that wish to 302dump over a specific period of time. 303The 304.Fl T 305option is mutually exclusive from the 306.Fl u 307option. 308.It Fl u 309Update the 310.Pa dumpdates 311file 312after a successful dump. 313The format of 314the 315.Pa dumpdates 316file 317is readable by people, consisting of one 318free format record per line: 319file system name, 320increment level 321and 322.Xr ctime 3 323format dump date. 324There may be only one entry per file system at each level. 325The 326.Pa dumpdates 327file 328may be edited to change any of the fields, 329if necessary. 330The default path for the 331.Pa dumpdates 332file is 333.Pa /etc/dumpdates , 334but the 335.Fl D 336option may be used to change it. 337.It Fl W 338Tell the operator what file systems need to be dumped. 339This information is gleaned from the files 340.Pa dumpdates 341and 342.Pa /etc/fstab . 343The 344.Fl W 345option causes 346.Nm 347to print out, for each file system in 348the 349.Pa dumpdates 350file 351the most recent dump date and level, 352and highlights those file systems that should be dumped. 353If the 354.Fl W 355option is set, all other options are ignored, and 356.Nm 357exits immediately. 358.It Fl w 359Is like 360.Fl W , 361but prints only those file systems which need to be dumped. 362.El 363.Pp 364Directories and regular files which have their 365.Dq nodump 366flag 367.Pq Dv UF_NODUMP 368set will be omitted along with everything under such directories, 369subject to the 370.Fl h 371option. 372.Pp 373The 374.Nm 375utility requires operator intervention on these conditions: 376end of tape, 377end of dump, 378tape write error, 379tape open error or 380disk read error (if there are more than a threshold of 32). 381In addition to alerting all operators implied by the 382.Fl n 383key, 384.Nm 385interacts with the operator on 386.Em dump's 387control terminal at times when 388.Nm 389can no longer proceed, 390or if something is grossly wrong. 391All questions 392.Nm 393poses 394.Em must 395be answered by typing 396.Dq yes 397or 398.Dq no , 399appropriately. 400.Pp 401Since making a dump involves a lot of time and effort for full dumps, 402.Nm 403checkpoints itself at the start of each tape volume. 404If writing that volume fails for some reason, 405.Nm 406will, 407with operator permission, 408restart itself from the checkpoint 409after the old tape has been rewound and removed, 410and a new tape has been mounted. 411.Pp 412The 413.Nm 414utility tells the operator what is going on at periodic intervals 415(every 5 minutes, or promptly after receiving 416.Dv SIGINFO ) , 417including usually low estimates of the number of blocks to write, 418the number of tapes it will take, the time to completion, and 419the time to the tape change. 420The output is verbose, 421so that others know that the terminal 422controlling 423.Nm 424is busy, 425and will be for some time. 426.Pp 427In the event of a catastrophic disk event, the time required 428to restore all the necessary backup tapes or files to disk 429can be kept to a minimum by staggering the incremental dumps. 430An efficient method of staggering incremental dumps 431to minimize the number of tapes follows: 432.Bl -bullet -offset indent 433.It 434Always start with a level 0 backup, for example: 435.Bd -literal -offset indent 436/sbin/dump -0u -f /dev/nsa0 /usr/src 437.Ed 438.Pp 439This should be done at set intervals, say once a month or once every two months, 440and on a set of fresh tapes that is saved forever. 441.It 442After a level 0, dumps of active file systems (file systems with files 443that change, depending on your partition layout some file systems may 444contain only data that does not change) are taken on a daily basis, 445using a modified Tower of Hanoi algorithm, 446with this sequence of dump levels: 447.Bd -literal -offset indent 4483 2 5 4 7 6 9 8 9 9 ... 449.Ed 450.Pp 451For the daily dumps, it should be possible to use a fixed number of tapes 452for each day, used on a weekly basis. 453Each week, a level 1 dump is taken, and 454the daily Hanoi sequence repeats beginning with 3. 455For weekly dumps, another fixed set of tapes per dumped file system is 456used, also on a cyclical basis. 457.El 458.Pp 459After several months or so, the daily and weekly tapes should get 460rotated out of the dump cycle and fresh tapes brought in. 461.Sh ENVIRONMENT 462.Bl -tag -width ".Ev TAPE" 463.It Ev TAPE 464The 465.Ar file 466or device to dump to if the 467.Fl f 468option is not used. 469.It Ev RMT 470Pathname of the remote 471.Xr rmt 8 472program. 473.It Ev RSH 474Pathname of a remote shell program, if not 475.Xr rsh 1 . 476.El 477.Sh FILES 478.Bl -tag -width /etc/dumpdates -compact 479.It Pa /dev/sa0 480default tape unit to dump to 481.It Pa /etc/dumpdates 482dump date records 483(this can be changed; 484see the 485.Fl D 486option) 487.It Pa /etc/fstab 488dump table: file systems and frequency 489.It Pa /etc/group 490to find group 491.Em operator 492.El 493.Sh EXIT STATUS 494Dump exits with zero status on success. 495Startup errors are indicated with an exit code of 1; 496abnormal termination is indicated with an exit code of 3. 497.Sh EXAMPLES 498Dumps the 499.Pa /u 500file system to DVDs using 501.Nm growisofs . 502Uses a 16MB cache, creates a snapshot of the dump, and records the 503.Pa dumpdates 504file. 505.Bd -literal 506/sbin/dump -0u -L -C16 -B4589840 -P 'growisofs -Z /dev/cd0=/dev/fd/0' /u 507.Ed 508.Sh DIAGNOSTICS 509Many, and verbose. 510.Sh SEE ALSO 511.Xr chflags 1 , 512.Xr fstab 5 , 513.Xr restore 8 , 514.Xr rmt 8 515.Sh HISTORY 516A 517.Nm 518utility appeared in 519.At v6 . 520.Sh BUGS 521Fewer than 32 read errors on the file system are ignored, though all 522errors will generate a warning message. 523This is a bit of a compromise. 524In practice, it is possible to generate read errors when doing dumps 525on mounted partitions if the file system is being modified while the 526.Nm 527is running. 528Since dumps are often done in an unattended fashion using 529.Xr cron 8 530jobs asking for Operator intervention would result in the 531.Nm 532dying. 533However, there is nothing wrong with a dump tape written when this sort 534of read error occurs, and there is no reason to terminate the 535.Nm . 536.Pp 537Each reel requires a new process, so parent processes for 538reels already written just hang around until the entire tape 539is written. 540.Pp 541The 542.Nm 543utility with the 544.Fl W 545or 546.Fl w 547options does not report file systems that have never been recorded 548in the 549.Pa dumpdates 550file, 551even if listed in 552.Pa /etc/fstab . 553.Pp 554It would be nice if 555.Nm 556knew about the dump sequence, 557kept track of the tapes scribbled on, 558told the operator which tape to mount when, 559and provided more assistance 560for the operator running 561.Xr restore 8 . 562.Pp 563The 564.Nm 565utility cannot do remote backups without being run as root, due to its 566security history. 567This will be fixed in a later version of 568.Fx . 569Presently, it works if you set it setuid (like it used to be), but this 570might constitute a security risk. 571