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.\" 3. 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 June 13, 2019 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.Sh DESCRIPTION 55The 56.Nm 57utility examines files 58on a file system 59and determines which files 60need to be backed up. 61These files 62are copied to the given disk, tape or other 63storage medium for safe keeping (see the 64.Fl f 65option below for doing remote backups). 66A dump that is larger than the output medium is broken into 67multiple volumes. 68On most media the size is determined by writing until an 69end-of-media indication is returned. 70This can be enforced 71by using the 72.Fl a 73option. 74.Pp 75On media that cannot reliably return an end-of-media indication 76(such as some cartridge tape drives) 77each volume is of a fixed size; 78the actual size is determined by the tape size and density and/or 79.Fl B 80options. 81By default, the same output file name is used for each volume 82after prompting the operator to change media. 83.Pp 84The file system to be dumped is specified by the argument 85.Ar filesystem 86as either its device-special file or its mount point 87(if that is in a standard entry in 88.Pa /etc/fstab ) . 89.Pp 90.Nm 91may also be invoked as 92.Nm rdump . 93The 94.Bx 4.3 95option syntax is implemented for backward compatibility, but 96is not documented here. 97.Pp 98The following options are supported by 99.Nm : 100.Bl -tag -width Ds 101.It Fl 0-9 102Dump levels. 103A level 0, full backup, 104guarantees the entire file system is copied 105(but see also the 106.Fl h 107option below). 108A level number above 0, 109incremental backup, 110tells dump to 111copy all files new or modified since the 112last dump of any lower level. 113The default level is 0. 114.It Fl a 115.Dq auto-size . 116Bypass all tape length considerations, and enforce writing 117until an end-of-media indication is returned. 118This fits best for most modern tape drives. 119Use of this option is particularly 120recommended when appending to an existing tape, or using a tape 121drive with hardware compression (where you can never be sure about 122the compression ratio). 123.It Fl B Ar records 124The number of kilobytes per output volume, except that if it is 125not an integer multiple of the output block size, 126the command uses the next smaller such multiple. 127This option overrides the calculation of tape size 128based on length and density. 129.It Fl b Ar blocksize 130The number of kilobytes per output block. 131The default block size is 10. 132.It Fl C Ar cachesize 133Specify the cache size in megabytes. 134This will greatly improve performance 135at the cost of 136.Nm 137possibly not noticing changes in the file system between passes. 138It is 139recommended that you always use this option when dumping a snapshot. 140Beware that 141.Nm 142forks, and the actual memory use may be larger than the specified cache 143size. 144The recommended cache size is between 8 and 32 (megabytes). 145.It Fl c 146Change the defaults for use with a cartridge tape drive, with a density 147of 8000 bpi, and a length of 1700 feet. 148.It Fl D Ar dumpdates 149Specify an alternate path to the 150.Pa dumpdates 151file. 152The default is 153.Pa /etc/dumpdates . 154.It Fl d Ar density 155Set tape density to 156.Ar density . 157The default is 1600BPI. 158.It Fl f Ar file 159Write the backup to 160.Ar file ; 161.Ar file 162may be a special device file 163like 164.Pa /dev/sa0 165(a tape drive), 166.Pa /dev/fd1 167(a floppy disk drive), 168an ordinary file, 169or 170.Sq Fl 171(the standard output). 172Multiple file names may be given as a single argument separated by commas. 173Each file will be used for one dump volume in the order listed; 174if the dump requires more volumes than the number of names given, 175the last file name will used for all remaining volumes after prompting 176for media changes. 177If the name of the file is of the form 178.Dq host:file , 179or 180.Dq user@host:file , 181.Nm 182writes to the named file on the remote host using 183.Xr rmt 8 . 184The default path name of the remote 185.Xr rmt 8 186program is 187.\" rmt path, is the path on the remote host 188.Pa /etc/rmt ; 189this can be overridden by the environment variable 190.Ev RMT . 191.It Fl P Ar pipecommand 192Use 193.Xr popen 3 194to execute the 195.Xr sh 1 196script string defined by 197.Ar pipecommand 198for the output device of each volume. 199This child pipeline's 200.Dv stdin 201.Pq Pa /dev/fd/0 202is redirected from the 203.Nm 204output stream, and the environment variable 205.Ev DUMP_VOLUME 206is set to the current volume number being written. 207After every volume, the writer side of the pipe is closed and 208.Ar pipecommand 209is executed again. 210Subject to the media size specified by 211.Fl B , 212each volume is written in this manner as if the output were a tape drive. 213.It Fl h Ar level 214Honor the user 215.Dq nodump 216flag 217.Pq Dv UF_NODUMP 218only for dumps at or above the given 219.Ar level . 220The default honor level is 1, 221so that incremental backups omit such files 222but full backups retain them. 223.It Fl L 224This option is to notify 225.Nm 226that it is dumping a live file system. 227To obtain a consistent dump image, 228.Nm 229takes a snapshot of the file system in the 230.Pa .snap 231directory in the root of the file system being dumped and 232then does a dump of the snapshot. 233The snapshot is unlinked as soon as the dump starts, and 234is thus removed when the dump is complete. 235This option is ignored for unmounted or read-only file systems. 236If the 237.Pa .snap 238directory does not exist in the root of the file system being dumped, 239a warning will be issued and the 240.Nm 241will revert to the standard behavior. 242This problem can be corrected by creating a 243.Pa .snap 244directory in the root of the file system to be dumped; 245its owner should be 246.Dq Li root , 247its group should be 248.Dq Li operator , 249and its mode should be 250.Dq Li 0770 . 251.It Fl n 252Whenever 253.Nm 254requires operator attention, 255notify all operators in the group 256.Dq operator 257by means similar to a 258.Xr wall 1 . 259.It Fl r 260Be rsync-friendly. 261Normally dump stores the date of the current 262and prior dump in numerous places throughout the dump. 263These scattered changes significantly slow down rsync or 264another incremental file transfer program when they are 265used to update a remote copy of a level 0 dump, 266since the date changes for each dump. 267This option sets both dates to the epoch, permitting 268rsync to be much more efficient when transferring a dump file. 269The 270.Fl r 271option can be used only to create level 0 dumps. 272A dump using the 273.Fl r 274option cannot be used as the basis for a later incremental dump. 275.It Fl R 276Be even more rsync-friendly. 277This option disables the storage of the actual inode access time 278(storing it instead as the inode's modified time). 279This option permits rsync to be even more efficient 280when transferring dumps generated from filesystems with numerous files 281which are not changing other than their access times. 282The 283.Fl R 284option also sets 285.Fl r . 286The 287.Fl R 288option can be used only to create level 0 dumps. 289A dump using the 290.Fl R 291option cannot be used as the basis for a later incremental dump. 292.It Fl S 293Display an estimate of the backup size and the number of 294tapes required, and exit without actually performing the dump. 295.It Fl s Ar feet 296Attempt to calculate the amount of tape needed 297at a particular density. 298If this amount is exceeded, 299.Nm 300prompts for a new tape. 301It is recommended to be a bit conservative on this option. 302The default tape length is 2300 feet. 303.It Fl T Ar date 304Use the specified date as the starting time for the dump 305instead of the time determined from looking in 306the 307.Pa dumpdates 308file. 309The format of date is the same as that of 310.Xr ctime 3 . 311This option is useful for automated dump scripts that wish to 312dump over a specific period of time. 313The 314.Fl T 315option is mutually exclusive from the 316.Fl u 317option. 318.It Fl u 319Update the 320.Pa dumpdates 321file 322after a successful dump. 323The format of 324the 325.Pa dumpdates 326file 327is readable by people, consisting of one 328free format record per line: 329file system name, 330increment level 331and 332.Xr ctime 3 333format dump date. 334There may be only one entry per file system at each level. 335The 336.Pa dumpdates 337file 338may be edited to change any of the fields, 339if necessary. 340The default path for the 341.Pa dumpdates 342file is 343.Pa /etc/dumpdates , 344but the 345.Fl D 346option may be used to change it. 347.It Fl W 348Tell the operator what file systems need to be dumped. 349This information is gleaned from the files 350.Pa dumpdates 351and 352.Pa /etc/fstab . 353The 354.Fl W 355option causes 356.Nm 357to print out, for each file system in 358the 359.Pa dumpdates 360file 361the most recent dump date and level, 362and highlights those file systems that should be dumped. 363If the 364.Fl W 365option is set, all other options are ignored, and 366.Nm 367exits immediately. 368.It Fl w 369Is like 370.Fl W , 371but prints only those file systems which need to be dumped. 372.El 373.Pp 374Directories and regular files which have their 375.Dq nodump 376flag 377.Pq Dv UF_NODUMP 378set will be omitted along with everything under such directories, 379subject to the 380.Fl h 381option. 382.Pp 383The 384.Nm 385utility requires operator intervention on these conditions: 386end of tape, 387end of dump, 388tape write error, 389tape open error or 390disk read error (if there are more than a threshold of 32). 391In addition to alerting all operators implied by the 392.Fl n 393key, 394.Nm 395interacts with the operator on 396.Em dump's 397control terminal at times when 398.Nm 399can no longer proceed, 400or if something is grossly wrong. 401All questions 402.Nm 403poses 404.Em must 405be answered by typing 406.Dq yes 407or 408.Dq no , 409appropriately. 410.Pp 411Since making a dump involves a lot of time and effort for full dumps, 412.Nm 413checkpoints itself at the start of each tape volume. 414If writing that volume fails for some reason, 415.Nm 416will, 417with operator permission, 418restart itself from the checkpoint 419after the old tape has been rewound and removed, 420and a new tape has been mounted. 421.Pp 422The 423.Nm 424utility tells the operator what is going on at periodic intervals 425(every 5 minutes, or promptly after receiving 426.Dv SIGINFO ) , 427including usually low estimates of the number of blocks to write, 428the number of tapes it will take, the time to completion, and 429the time to the tape change. 430The output is verbose, 431so that others know that the terminal 432controlling 433.Nm 434is busy, 435and will be for some time. 436.Pp 437In the event of a catastrophic disk event, the time required 438to restore all the necessary backup tapes or files to disk 439can be kept to a minimum by staggering the incremental dumps. 440An efficient method of staggering incremental dumps 441to minimize the number of tapes follows: 442.Bl -bullet -offset indent 443.It 444Always start with a level 0 backup, for example: 445.Bd -literal -offset indent 446/sbin/dump -0u -f /dev/nsa0 /usr/src 447.Ed 448.Pp 449This should be done at set intervals, say once a month or once every two months, 450and on a set of fresh tapes that is saved forever. 451.It 452After a level 0, dumps of active file systems (file systems with files 453that change, depending on your partition layout some file systems may 454contain only data that does not change) are taken on a daily basis, 455using a modified Tower of Hanoi algorithm, 456with this sequence of dump levels: 457.Bd -literal -offset indent 4583 2 5 4 7 6 9 8 9 9 ... 459.Ed 460.Pp 461For the daily dumps, it should be possible to use a fixed number of tapes 462for each day, used on a weekly basis. 463Each week, a level 1 dump is taken, and 464the daily Hanoi sequence repeats beginning with 3. 465For weekly dumps, another fixed set of tapes per dumped file system is 466used, also on a cyclical basis. 467.El 468.Pp 469After several months or so, the daily and weekly tapes should get 470rotated out of the dump cycle and fresh tapes brought in. 471.Sh ENVIRONMENT 472.Bl -tag -width ".Ev TAPE" 473.It Ev TAPE 474The 475.Ar file 476or device to dump to if the 477.Fl f 478option is not used. 479.It Ev RMT 480Pathname of the remote 481.Xr rmt 8 482program. 483.It Ev RSH 484Pathname of a remote shell program, if not 485.Xr rsh 1 . 486.El 487.Sh FILES 488.Bl -tag -width /etc/dumpdates -compact 489.It Pa /dev/sa0 490default tape unit to dump to 491.It Pa /etc/dumpdates 492dump date records 493(this can be changed; 494see the 495.Fl D 496option) 497.It Pa /etc/fstab 498dump table: file systems and frequency 499.It Pa /etc/group 500to find group 501.Em operator 502.El 503.Sh EXIT STATUS 504Dump exits with zero status on success. 505Startup errors are indicated with an exit code of 1; 506abnormal termination is indicated with an exit code of 3. 507.Sh EXAMPLES 508Dumps the 509.Pa /u 510file system to DVDs using 511.Nm growisofs . 512Uses a 16MB cache, creates a snapshot of the dump, and records the 513.Pa dumpdates 514file. 515.Bd -literal 516/sbin/dump -0u -L -C16 -B4589840 -P 'growisofs -Z /dev/cd0=/dev/fd/0' /u 517.Ed 518.Sh DIAGNOSTICS 519Many, and verbose. 520.Sh SEE ALSO 521.Xr chflags 1 , 522.Xr fstab 5 , 523.Xr restore 8 , 524.Xr rmt 8 525.Sh HISTORY 526A 527.Nm 528utility appeared in 529.At v4 . 530.Sh BUGS 531Fewer than 32 read errors on the file system are ignored, though all 532errors will generate a warning message. 533This is a bit of a compromise. 534In practice, it is possible to generate read errors when doing dumps 535on mounted partitions if the file system is being modified while the 536.Nm 537is running. 538Since dumps are often done in an unattended fashion using 539.Xr cron 8 540jobs asking for Operator intervention would result in the 541.Nm 542dying. 543However, there is nothing wrong with a dump tape written when this sort 544of read error occurs, and there is no reason to terminate the 545.Nm . 546.Pp 547Each reel requires a new process, so parent processes for 548reels already written just hang around until the entire tape 549is written. 550.Pp 551The 552.Nm 553utility with the 554.Fl W 555or 556.Fl w 557options does not report file systems that have never been recorded 558in the 559.Pa dumpdates 560file, 561even if listed in 562.Pa /etc/fstab . 563.Pp 564It would be nice if 565.Nm 566knew about the dump sequence, 567kept track of the tapes scribbled on, 568told the operator which tape to mount when, 569and provided more assistance 570for the operator running 571.Xr restore 8 . 572.Pp 573The 574.Nm 575utility cannot do remote backups without being run as root, due to its 576security history. 577This will be fixed in a later version of 578.Fx . 579Presently, it works if you set it setuid (like it used to be), but this 580might constitute a security risk. 581