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 December 22, 2005 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 0123456789acLnSu 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 removed when the dump is complete. 236This option is ignored for unmounted or read-only file systems. 237If the 238.Pa .snap 239directory does not exist in the root of the file system being dumped, 240a warning will be issued and the 241.Nm 242will revert to the standard behavior. 243This problem can be corrected by creating a 244.Pa .snap 245directory in the root of the file system to be dumped; 246its owner should be 247.Dq Li root , 248its group should be 249.Dq Li operator , 250and its mode should be 251.Dq Li 0770 . 252.It Fl n 253Whenever 254.Nm 255requires operator attention, 256notify all operators in the group 257.Dq operator 258by means similar to a 259.Xr wall 1 . 260.It Fl S 261Display an estimate of the backup size and the number of 262tapes required, and exit without actually performing the dump. 263.It Fl s Ar feet 264Attempt to calculate the amount of tape needed 265at a particular density. 266If this amount is exceeded, 267.Nm 268prompts for a new tape. 269It is recommended to be a bit conservative on this option. 270The default tape length is 2300 feet. 271.It Fl T Ar date 272Use the specified date as the starting time for the dump 273instead of the time determined from looking in 274a warning will be issued and the 275.Pa dumpdates 276file. 277The format of date is the same as that of 278.Xr ctime 3 . 279This option is useful for automated dump scripts that wish to 280dump over a specific period of time. 281The 282.Fl T 283option is mutually exclusive from the 284.Fl u 285option. 286.It Fl u 287Update the 288.Pa dumpdates 289file 290after a successful dump. 291The format of 292the 293.Pa dumpdates 294file 295is readable by people, consisting of one 296free format record per line: 297file system name, 298increment level 299and 300.Xr ctime 3 301format dump date. 302There may be only one entry per file system at each level. 303The 304.Pa dumpdates 305file 306may be edited to change any of the fields, 307if necessary. 308The default path for the 309.Pa dumpdates 310file is 311.Pa /etc/dumpdates , 312but the 313.Fl D 314option may be used to change it. 315.It Fl W 316Tell the operator what file systems need to be dumped. 317This information is gleaned from the files 318.Pa dumpdates 319and 320.Pa /etc/fstab . 321The 322.Fl W 323option causes 324.Nm 325to print out, for each file system in 326the 327.Pa dumpdates 328file 329the most recent dump date and level, 330and highlights those file systems that should be dumped. 331If the 332.Fl W 333option is set, all other options are ignored, and 334.Nm 335exits immediately. 336.It Fl w 337Is like 338.Fl W , 339but prints only those file systems which need to be dumped. 340.El 341.Pp 342Directories and regular files which have their 343.Dq nodump 344flag 345.Pq Dv UF_NODUMP 346set will be omitted along with everything under such directories, 347subject to the 348.Fl h 349option. 350.Pp 351The 352.Nm 353utility requires operator intervention on these conditions: 354end of tape, 355end of dump, 356tape write error, 357tape open error or 358disk read error (if there are more than a threshold of 32). 359In addition to alerting all operators implied by the 360.Fl n 361key, 362.Nm 363interacts with the operator on 364.Em dump's 365control terminal at times when 366.Nm 367can no longer proceed, 368or if something is grossly wrong. 369All questions 370.Nm 371poses 372.Em must 373be answered by typing 374.Dq yes 375or 376.Dq no , 377appropriately. 378.Pp 379Since making a dump involves a lot of time and effort for full dumps, 380.Nm 381checkpoints itself at the start of each tape volume. 382If writing that volume fails for some reason, 383.Nm 384will, 385with operator permission, 386restart itself from the checkpoint 387after the old tape has been rewound and removed, 388and a new tape has been mounted. 389.Pp 390The 391.Nm 392utility tells the operator what is going on at periodic intervals 393(every 5 minutes, or promptly after receiving 394.Dv SIGINFO ) , 395including usually low estimates of the number of blocks to write, 396the number of tapes it will take, the time to completion, and 397the time to the tape change. 398The output is verbose, 399so that others know that the terminal 400controlling 401.Nm 402is busy, 403and will be for some time. 404.Pp 405In the event of a catastrophic disk event, the time required 406to restore all the necessary backup tapes or files to disk 407can be kept to a minimum by staggering the incremental dumps. 408An efficient method of staggering incremental dumps 409to minimize the number of tapes follows: 410.Bl -bullet -offset indent 411.It 412Always start with a level 0 backup, for example: 413.Bd -literal -offset indent 414/sbin/dump -0u -f /dev/nsa0 /usr/src 415.Ed 416.Pp 417This should be done at set intervals, say once a month or once every two months, 418and on a set of fresh tapes that is saved forever. 419.It 420After a level 0, dumps of active file systems (file systems with files 421that change, depending on your partition layout some file systems may 422contain only data that does not change) are taken on a daily basis, 423using a modified Tower of Hanoi algorithm, 424with this sequence of dump levels: 425.Bd -literal -offset indent 4263 2 5 4 7 6 9 8 9 9 ... 427.Ed 428.Pp 429For the daily dumps, it should be possible to use a fixed number of tapes 430for each day, used on a weekly basis. 431Each week, a level 1 dump is taken, and 432the daily Hanoi sequence repeats beginning with 3. 433For weekly dumps, another fixed set of tapes per dumped file system is 434used, also on a cyclical basis. 435.El 436.Pp 437After several months or so, the daily and weekly tapes should get 438rotated out of the dump cycle and fresh tapes brought in. 439.Sh ENVIRONMENT 440.Bl -tag -width ".Ev TAPE" 441.It Ev TAPE 442The 443.Ar file 444or device to dump to if the 445.Fl f 446option is not used. 447.It Ev RMT 448Pathname of the remote 449.Xr rmt 8 450program. 451.It Ev RSH 452Pathname of a remote shell program, if not 453.Xr rsh 1 . 454.El 455.Sh EXAMPLES 456Dumps the "/u" file system to dvds using growisofs. 457Uses a 16MB cache and creates a snapshot of the dump and records the 458dumpdates file. 459.Bd -literal 460/sbin/dump -0u -L -C16 -B4589840 -P 'growisofs -Z /dev/cd0=/dev/fd/0' /u 461.Ed 462.Sh FILES 463.Bl -tag -width /etc/dumpdates -compact 464.It Pa /dev/sa0 465default tape unit to dump to 466.It Pa /etc/dumpdates 467dump date records 468(this can be changed; 469see the 470.Fl D 471option) 472.It Pa /etc/fstab 473dump table: file systems and frequency 474.It Pa /etc/group 475to find group 476.Em operator 477.El 478.Sh EXIT STATUS 479Dump exits with zero status on success. 480Startup errors are indicated with an exit code of 1; 481abnormal termination is indicated with an exit code of 3. 482.Sh DIAGNOSTICS 483Many, and verbose. 484.Sh SEE ALSO 485.Xr chflags 1 , 486.Xr fstab 5 , 487.Xr restore 8 , 488.Xr rmt 8 489.Sh HISTORY 490A 491.Nm 492utility appeared in 493.At v6 . 494.Sh BUGS 495Fewer than 32 read errors on the file system are ignored, though all 496errors will generate a warning message. 497This is a bit of a compromise. 498In practice, it is possible to generate read errors when doing dumps 499on mounted partitions if the file system is being modified while the 500.Nm 501is running. 502Since dumps are often done in an unattended fashion using 503.Xr cron 8 504jobs asking for Operator intervention would result in the 505.Nm 506dying. 507However, there is nothing wrong with a dump tape written when this sort 508of read error occurs, and there is no reason to terminate the 509.Nm . 510.Pp 511Each reel requires a new process, so parent processes for 512reels already written just hang around until the entire tape 513is written. 514.Pp 515The 516.Nm 517utility with the 518.Fl W 519or 520.Fl w 521options does not report file systems that have never been recorded 522in the 523.Pa dumpdates 524file, 525even if listed in 526.Pa /etc/fstab . 527.Pp 528It would be nice if 529.Nm 530knew about the dump sequence, 531kept track of the tapes scribbled on, 532told the operator which tape to mount when, 533and provided more assistance 534for the operator running 535.Xr restore 8 . 536.Pp 537The 538.Nm 539utility cannot do remote backups without being run as root, due to its 540security history. 541This will be fixed in a later version of 542.Fx . 543Presently, it works if you set it setuid (like it used to be), but this 544might constitute a security risk. 545