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 March 1, 2002 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.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 filesystem 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 filesystems. 237If the 238.Pa .snap 239directory does not exist in the root of the filesystem being dumped, 240the dump will fail. 241This problem can be corrected by creating a 242.Pa .snap 243directory in the root of the filesystem to be dumped; 244its owner should be root, its group should be operator, 245and its mode should be 0770. 246.It Fl n 247Whenever 248.Nm 249requires operator attention, 250notify all operators in the group 251.Dq operator 252by means similar to a 253.Xr wall 1 . 254.It Fl S 255Display an estimate of the backup size and the number of 256tapes required, and exit without actually performing the dump. 257.It Fl s Ar feet 258Attempt to calculate the amount of tape needed 259at a particular density. 260If this amount is exceeded, 261.Nm 262prompts for a new tape. 263It is recommended to be a bit conservative on this option. 264The default tape length is 2300 feet. 265.It Fl T Ar date 266Use the specified date as the starting time for the dump 267instead of the time determined from looking in 268the 269.Pa dumpdates 270file. 271The format of date is the same as that of 272.Xr ctime 3 . 273This option is useful for automated dump scripts that wish to 274dump over a specific period of time. 275The 276.Fl T 277option is mutually exclusive from the 278.Fl u 279option. 280.It Fl u 281Update the 282.Pa dumpdates 283file 284after a successful dump. 285The format of 286the 287.Pa dumpdates 288file 289is readable by people, consisting of one 290free format record per line: 291file system name, 292increment level 293and 294.Xr ctime 3 295format dump date. 296There may be only one entry per file system at each level. 297The 298.Pa dumpdates 299file 300may be edited to change any of the fields, 301if necessary. 302The default path for the 303.Pa dumpdates 304file is 305.Pa /etc/dumpdates , 306but the 307.Fl D 308option may be used to change it. 309.It Fl W 310Tell the operator what file systems need to be dumped. 311This information is gleaned from the files 312.Pa dumpdates 313and 314.Pa /etc/fstab . 315The 316.Fl W 317option causes 318.Nm 319to print out, for each file system in 320the 321.Pa dumpdates 322file 323the most recent dump date and level, 324and highlights those file systems that should be dumped. 325If the 326.Fl W 327option is set, all other options are ignored, and 328.Nm 329exits immediately. 330.It Fl w 331Is like 332.Fl W , 333but prints only those file systems which need to be dumped. 334.El 335.Pp 336Directories and regular files which have their 337.Dq nodump 338flag 339.Pq Dv UF_NODUMP 340set will be omitted along with everything under such directories, 341subject to the 342.Fl h 343option. 344.Pp 345The 346.Nm 347utility requires operator intervention on these conditions: 348end of tape, 349end of dump, 350tape write error, 351tape open error or 352disk read error (if there are more than a threshold of 32). 353In addition to alerting all operators implied by the 354.Fl n 355key, 356.Nm 357interacts with the operator on 358.Em dump's 359control terminal at times when 360.Nm 361can no longer proceed, 362or if something is grossly wrong. 363All questions 364.Nm 365poses 366.Em must 367be answered by typing 368.Dq yes 369or 370.Dq no , 371appropriately. 372.Pp 373Since making a dump involves a lot of time and effort for full dumps, 374.Nm 375checkpoints itself at the start of each tape volume. 376If writing that volume fails for some reason, 377.Nm 378will, 379with operator permission, 380restart itself from the checkpoint 381after the old tape has been rewound and removed, 382and a new tape has been mounted. 383.Pp 384The 385.Nm 386utility tells the operator what is going on at periodic intervals 387(every 5 minutes, or promptly after receiving 388.Dv SIGINFO ) , 389including usually low estimates of the number of blocks to write, 390the number of tapes it will take, the time to completion, and 391the time to the tape change. 392The output is verbose, 393so that others know that the terminal 394controlling 395.Nm 396is busy, 397and will be for some time. 398.Pp 399In the event of a catastrophic disk event, the time required 400to restore all the necessary backup tapes or files to disk 401can be kept to a minimum by staggering the incremental dumps. 402An efficient method of staggering incremental dumps 403to minimize the number of tapes follows: 404.Bl -bullet -offset indent 405.It 406Always start with a level 0 backup, for example: 407.Bd -literal -offset indent 408/sbin/dump -0u -f /dev/nsa0 /usr/src 409.Ed 410.Pp 411This should be done at set intervals, say once a month or once every two months, 412and on a set of fresh tapes that is saved forever. 413.It 414After a level 0, dumps of active file systems (file systems with files 415that change, depending on your partition layout some file systems may 416contain only data that does not change) are taken on a daily basis, 417using a modified Tower of Hanoi algorithm, 418with this sequence of dump levels: 419.Bd -literal -offset indent 4203 2 5 4 7 6 9 8 9 9 ... 421.Ed 422.Pp 423For the daily dumps, it should be possible to use a fixed number of tapes 424for each day, used on a weekly basis. 425Each week, a level 1 dump is taken, and 426the daily Hanoi sequence repeats beginning with 3. 427For weekly dumps, another fixed set of tapes per dumped file system is 428used, also on a cyclical basis. 429.El 430.Pp 431After several months or so, the daily and weekly tapes should get 432rotated out of the dump cycle and fresh tapes brought in. 433.Sh ENVIRONMENT 434.Bl -tag -width ".Ev TAPE" 435.It Ev TAPE 436Device from which to read backup. 437.It Ev RMT 438Pathname of the remote 439.Xr rmt 8 440program. 441.It Ev RSH 442Pathname of remote shell program, if not 443.Xr rsh 1 . 444.El 445.Sh FILES 446.Bl -tag -width /etc/dumpdates -compact 447.It Pa /dev/sa0 448default tape unit to dump to 449.It Pa /etc/dumpdates 450dump date records 451(this can be changed; 452see the 453.Fl D 454option) 455.It Pa /etc/fstab 456dump table: file systems and frequency 457.It Pa /etc/group 458to find group 459.Em operator 460.El 461.Sh SEE ALSO 462.Xr chflags 1 , 463.Xr fstab 5 , 464.Xr restore 8 , 465.Xr rmt 8 466.Sh DIAGNOSTICS 467Many, and verbose. 468.Pp 469Dump exits with zero status on success. 470Startup errors are indicated with an exit code of 1; 471abnormal termination is indicated with an exit code of 3. 472.Sh BUGS 473Fewer than 32 read errors on the file system are ignored, though all 474errors will generate a warning message. 475This is a bit of a compromise. 476In practice it is possible to generate read errors when doing dumps 477on mounted partitions if the file system is being modified while the 478dump is running. 479Since dumps are often done in an unattended fashion using 480.Xr cron 8 481jobs asking for Operator intervention would result in the dump dying. 482However there is nothing wrong with a dump tape written when this sort 483of read error occurs and there is no reason to terminate the dump. 484.Pp 485Each reel requires a new process, so parent processes for 486reels already written just hang around until the entire tape 487is written. 488.Pp 489The 490.Nm 491utility with the 492.Fl W 493or 494.Fl w 495options does not report file systems that have never been recorded 496in the 497.Pa dumpdates 498file, 499even if listed in 500.Pa /etc/fstab . 501.Pp 502It would be nice if 503.Nm 504knew about the dump sequence, 505kept track of the tapes scribbled on, 506told the operator which tape to mount when, 507and provided more assistance 508for the operator running 509.Xr restore 8 . 510.Pp 511The 512.Nm 513utility cannot do remote backups without being run as root, due to its 514security history. 515This will be fixed in a later version of 516.Fx . 517Presently, it works if you set it setuid (like it used to be), but this 518might constitute a security risk. 519.Sh HISTORY 520A 521.Nm 522utility appeared in 523.At v6 . 524