1.\" $NetBSD: dump.8,v 1.72 2019/08/19 18:12:50 perseant Exp $ 2.\" 3.\" Copyright (c) 1980, 1991, 1993 4.\" Regents of the University of California. 5.\" All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)dump.8 8.3 (Berkeley) 5/1/95 32.\" 33.Dd March 25, 2019 34.Dt DUMP 8 35.Os 36.Sh NAME 37.Nm dump , 38.Nm rdump 39.Nd file system backup 40.Sh SYNOPSIS 41.Nm 42.Op Fl 0123456789aceFinStuX 43.Op Fl B Ar records 44.Op Fl b Ar blocksize 45.Op Fl D Ar dumpdates-file 46.Op Fl d Ar density 47.Op Fl f Ar file 48.Op Fl h Ar level 49.Op Fl k Ar read-blocksize 50.Op Fl L Ar label 51.Op Fl l Ar timeout 52.Op Fl r Ar cachesize 53.Op Fl s Ar feet 54.Op Fl T Ar date 55.Op Fl U Ar dumpdev 56.Op Fl x Ar snap-backup 57.Ar files-to-dump 58.Nm 59.Op Fl W Li \&| Fl w 60.Pp 61.in -\n[indent-synopsis]u 62.Pf ( Bx 4.3 63option syntax is implemented for backward compatibility, but 64not documented here.) 65.Sh DESCRIPTION 66.Nm 67examines files on a file system and determines which files need to 68be backed up. 69These files are copied to the given disk, tape or other storage 70medium for safe keeping (see the 71.Fl f 72option below for doing remote backups). 73A dump that is larger than the output medium is broken into 74multiple volumes. 75On most media the size is determined by writing until an 76end-of-media indication is returned. 77This can be enforced by using the 78.Fl a 79option. 80.Pp 81On media that cannot reliably return an end-of-media indication 82(such as some cartridge tape drives) each volume is of a fixed size; 83the actual size is determined by the tape size and density and/or 84block count options below. 85By default, the same output file name is used for each volume 86after prompting the operator to change media. 87.Pp 88.Ar files-to-dump 89is either a single file system, 90or a list of files and directories on a single file system to be backed 91up as a subset of the file system. 92In the former case, 93.Ar files-to-dump 94may be the device of a file system, 95the path to a currently mounted file system, 96the path to an unmounted file system listed in 97.Pa /etc/fstab , 98or, if 99.Fl F 100is given, a file system image. 101In the latter case, certain restrictions are placed on the backup: 102.Fl u 103is ignored, the only dump level that is supported is 104.Fl 0 , 105and all of the files must reside on the same file system. 106.Pp 107Any files with the superuser 108.Qq log 109flag 110.Pq Dv SF_LOG 111set will be skipped. 112These files are assumed to be 113.Xr wapbl 4 114journal files and will not be backed up. 115.Pp 116The following options are supported by 117.Nm : 118.Bl -tag -width Ds 119.It Fl 0\-9 120Dump levels. 121A level 0, full backup, guarantees the entire file system is copied 122(but see also the 123.Fl h 124option below). 125A level number above 0, incremental backup, 126tells dump to copy all files new or modified since the 127last dump of a lower level (but see also the 128.Fl i 129option below). 130The default level is 9. 131.It Fl a 132.Dq auto-size . 133Bypass all tape length considerations, and enforce writing 134until an end-of-media indication is returned. 135This fits best for most modern tape drives. 136Use of this option is particularly recommended when appending to an 137existing tape, or using a tape drive with hardware compression (where 138you can never be sure about the compression ratio). 139.It Fl B Ar records 140The number of kilobytes per volume, rounded 141down to a multiple of the blocksize. 142This option overrides the calculation of tape size 143based on length and density. 144.It Fl b Ar blocksize 145The number of kilobytes per dump record. 146.It Fl c 147Modify the calculation of the default density and tape size to be more 148appropriate for cartridge tapes. 149.It Fl D Ar dumpdates-file 150Use the given file as a record of dump dates instead of 151.Pa /etc/dumpdates . 152.It Fl d Ar density 153Set tape density to 154.Ar density . 155The default is 1600 Bits Per Inch (BPI). 156.It Fl e 157Eject tape automatically if a tape change is required. 158.It Fl F 159Indicates that 160.Ar files-to-dump 161is a file system image. 162.It Fl f Ar file 163Write the backup to 164.Ar file ; 165.Ar file 166may be a special device file like 167.Pa /dev/rst0 168(a tape drive), 169.Pa /dev/rsd1c 170(a disk drive), 171an ordinary file, or 172.Ql 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 be used for all remaining volumes after prompting 178for media changes. 179If the name of the file is of the form 180.Qq host:file , 181or 182.Qq user@host:file , 183.Nm 184writes to the named file on the remote host using 185.Xr rmt 8 . 186Note that methods more secure than 187.Xr rsh 1 188.Pq such as Xr ssh 1 189can be used to invoke 190.Xr rmt 8 191on the remote host, via the environment variable 192.Ev RCMD_CMD . 193See 194.Xr rcmd 3 195for more details. 196.It Fl h Ar level 197Honor the user 198.Qq nodump 199flag 200.Pq Dv UF_NODUMP 201only for dumps at or above the given 202.Ar level . 203The default honor level is 1, 204so that incremental backups omit such files 205but full backups retain them. 206.It Fl i 207The dump is treated as level 9 but takes into account a previous 208level 9, if one exists. 209This makes it possible to perform a 210.Dq true incremental 211dump. 212.It Fl k Ar read-blocksize 213The size in kilobytes of the read buffers, rounded up to a multiple of the 214file system block size. 215Default is the value of the 216.Xr sysctl 7 217kern.maxphys. 218.It Fl L Ar label 219The user-supplied text string 220.Ar label 221is placed into the dump header, where tools like 222.Xr restore 8 223and 224.Xr file 1 225can access it. 226Note that this label is limited to be at most LBLSIZE 227(currently 16) characters, which must include the terminating 228.Ql \e0 . 229.It Fl l Ar timeout 230If a tape change is required, eject the tape and wait for the drive to 231be ready again. 232This is to be used with tape changers which automatically load 233the next tape when the tape is ejected. 234If after the timeout (in seconds) the drive is not ready 235.Nm 236falls back to the default behavior, 237and prompts the operator for the next tape. 238.It Fl n 239Whenever 240.Nm 241requires operator attention, 242notify all operators in the group 243.Qq operator 244using 245.Xr wall 1 . 246.It Fl r Ar cachesize 247Use that many buffers for read cache operations. 248A value of zero disables the read cache altogether, higher values 249improve read performance by reading larger data blocks from the 250disk and maintaining them in an LRU cache. 251See the 252.Fl k 253option for the size of the buffers. 254Maximum is 512, the size of the cache is 255limited to 15% of the avail RAM by default. 256.It Fl S 257Display an estimate of the backup size and the number of tapes 258required, and exit without actually performing the dump. 259.It Fl s Ar feet 260Attempt to calculate the amount of tape needed 261at a particular density. 262If this amount is exceeded, 263.Nm 264prompts for a new tape. 265It is recommended to be a bit conservative on this option. 266The default tape length is 2300 feet. 267.It Fl T Ar date 268Use the specified date as the starting time for the dump 269instead of the time determined from looking in 270.Pa /etc/dumpdates . 271The format of 272.Ar date 273is the same as that of 274.Xr ctime 3 . 275This option is useful for automated dump scripts that wish to 276dump over a specific period of time. 277The 278.Fl T 279option and the 280.Fl u 281option are mutually exclusive. 282.It Fl t 283All informational log messages printed by 284.Nm 285will have the time prepended to them. 286Also, the completion time interval estimations 287will have the estimated time at which the dump 288will complete printed at the end of the line. 289.It Fl u 290Update the file 291.Pa /etc/dumpdates 292after a successful dump. 293The format of 294.Pa /etc/dumpdates 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 file 304.Pa /etc/dumpdates 305may be edited to change any of the fields, 306if necessary. 307If the 308.Fl T 309option is used or if a list of files or subdirectories is being dumped 310(as opposed to an entire file system), then 311.Fl u 312is ignored. 313.It Fl U Ar dumpdev 314Same as 315.Fl u 316but specifies the device in 317.Pa /etc/dumpdates 318as 319.Ar dumpdev . 320This option can be used with subdir dumps and with the 321.Fl T 322option. 323.It Fl W 324.Nm 325tells the operator what file systems need to be dumped. 326This information is gleaned from the files 327.Pa /etc/dumpdates 328and 329.Pa /etc/fstab . 330The 331.Fl W 332option causes 333.Nm 334to print out, for each file system in 335.Pa /etc/dumpdates 336the most recent dump date and level, 337and highlights those file systems that should be dumped. 338If the 339.Fl W 340option is set, all other options are ignored, and 341.Nm 342exits immediately. 343.It Fl w 344Like 345.Fl W , 346but prints only those file systems which need to be dumped. 347.It Fl X 348Similar to 349.Fl x 350but uses a file system internal snapshot on the file system to be dumped. 351.It Fl x Ar snap-backup 352Use a snapshot with 353.Ar snap-backup 354as backup for this dump. 355See 356.Xr fss 4 357for more details. 358.El 359.Pp 360If 361.Nm 362honors the 363.Qq nodump 364flag 365.Pq Dv UF_NODUMP , 366files with the 367.Qq nodump 368flag will not be backed up. 369If a directory has the 370.Qq nodump 371flag, this directory and any file or directory under it will not be backed up. 372.Pp 373.Nm 374requires operator intervention on these conditions: 375end of tape, 376end of dump, 377tape write error, 378tape open error or 379disk read error (if there are more than a threshold of 32). 380In addition to alerting all operators implied by the 381.Fl n 382option, 383.Nm 384interacts with the operator on 385.Nm Ns 's 386control terminal at times when 387.Nm 388can no longer proceed, 389or if something is grossly wrong. 390All questions 391.Nm 392poses 393.Em must 394be answered by typing 395.Qq yes 396or 397.Qq no , 398appropriately. 399.Pp 400Since making a dump involves a lot of time and effort for full dumps, 401.Nm 402checkpoints itself at the start of each tape volume. 403If writing that volume fails for some reason, 404.Nm 405will, 406with operator permission, 407restart itself from the checkpoint 408after the old tape has been rewound and removed, 409and a new tape has been mounted. 410.Pp 411.Nm 412tells the operator what is going on at periodic intervals, 413including usually low estimates of the number of blocks to write, 414the number of tapes it will take, the time to completion, and 415the time to the tape change. 416The output is verbose, 417so that others know that the terminal 418controlling 419.Nm 420is busy, 421and will be for some time. 422.Pp 423In the event of a catastrophic disk event, the time required 424to restore all the necessary backup tapes or files to disk 425can be kept to a minimum by staggering the incremental dumps. 426An efficient method of staggering incremental dumps 427to minimize the number of tapes follows: 428.Bl -bullet -offset indent 429.It 430Always start with a level 0 backup, for example: 431.Bd -literal -offset indent 432/sbin/dump -0u -f /dev/nrst1 /usr/src 433.Ed 434.Pp 435This should be done at set intervals, say once a month or once every two months, 436and on a set of fresh tapes that is saved forever. 437.It 438After a level 0, dumps of active file 439systems are taken on a daily basis, 440using a modified Tower of Hanoi algorithm, 441with this sequence of dump levels: 442.Bd -literal -offset indent 4433 2 5 4 7 6 9 8 9 9 ... 444.Ed 445.Pp 446For the daily dumps, it should be possible to use a fixed number of tapes 447for each day, used on a weekly basis. 448Each week, a level 1 dump is taken, and 449the daily Hanoi sequence repeats beginning with 3. 450For weekly dumps, another fixed set of tapes per dumped file system is 451used, also on a cyclical basis. 452.El 453.Pp 454After several months or so, the daily and weekly tapes should get 455rotated out of the dump cycle and fresh tapes brought in. 456.Pp 457If 458.Nm 459receives a 460.Dv SIGINFO 461signal 462(see the 463.Qq status 464argument of 465.Xr stty 1 ) 466whilst a backup is in progress, statistics on the amount completed, 467current transfer rate, and estimated finished time, will be written 468to the standard error output. 469.Pp 470The historic alternate name 471.Nm rdump 472was once required when dumping to a remote host. 473This functionality is now built into 474.Nm 475itself. 476.Sh ENVIRONMENT 477If the following environment variables exist, they are used by 478.Nm . 479.Bl -tag -width Fl 480.It Ev TAPE 481If no -f option was specified, 482.Nm 483will use the device specified via 484.Ev TAPE 485as the dump device. 486.Ev TAPE 487may be of the form 488.Qq tapename , 489.Qq host:tapename , 490or 491.Qq user@host:tapename . 492.It Ev RCMD_CMD 493.Nm 494will use 495.Ev RCMD_CMD 496rather than 497.Xr rsh 1 498to invoke 499.Xr rmt 8 500on the remote machine. 501.It Ev TIMEFORMAT 502can be used to control the format of the timestamps produced by the 503.Fl t 504option. 505.Ev TIMEFORMAT 506is a string containing embedded formatting commands for 507.Xr strftime 3 . 508The total formatted string is limited to about 80 characters, if this 509limit is exceeded then 510.Qo 511ERROR: TIMEFORMAT too long, reverting to default 512.Qc 513will be printed and the time format will revert to the default one. 514If 515.Ev TIMEFORMAT 516is not set then the format string defaults to 517.Qo 518%T %Z 519.Qc 520.El 521.Sh FILES 522.Bl -tag -width /etc/dumpdates -compact 523.It Pa /dev/nrst0 524default tape unit to use. 525Taken from 526.Dv _PATH_DEFTAPE 527in 528.Pa /usr/include/paths.h . 529.It Pa /dev/rst* 530raw SCSI tape interface 531.It Pa /etc/dumpdates 532dump date records 533.It Pa /etc/fstab 534dump table: file systems and frequency 535.It Pa /etc/group 536to find group 537.Em operator 538.El 539.Sh DIAGNOSTICS 540Many, and verbose. 541.Pp 542.Nm 543exits with zero status on success. 544Startup errors are indicated with an exit code of 1; 545abnormal termination is indicated with an exit code of 3. 546.Sh SEE ALSO 547.Xr chflags 1 , 548.Xr rcmd 1 , 549.Xr stty 1 , 550.Xr wall 1 , 551.Xr fts 3 , 552.Xr rcmd 3 , 553.Xr fss 4 , 554.Xr st 4 , 555.Xr fstab 5 , 556.Xr environ 7 , 557.Xr restore 8 , 558.Xr rmt 8 559.Sh HISTORY 560A 561.Nm 562command appeared in 563.At v4 . 564.Pp 565The 566.Fl i 567flag was inspired by the 568.Fl x 569flag from Sun's Solstice Backup utility. 570.Sh BUGS 571At least the following caveats can be mentioned. 572.Bl -bullet 573.It 574Fewer than 32 read errors on the file system are ignored. 575.It 576Each reel requires a new process, so parent processes for 577reels already written just hang around until the entire tape 578is written. 579.It 580.Nm 581with the 582.Fl W 583or 584.Fl w 585options does not report file systems that have never been recorded 586in 587.Pa /etc/dumpdates , 588even if listed in 589.Pa /etc/fstab . 590.It 591When dumping a list of files or subdirectories, access privileges are 592required to scan the directory (as this is done via the 593.Xr fts 3 594routines rather than directly accessing the file system). 595.It 596It would be nice if 597.Nm 598knew about the dump sequence, 599kept track of the tapes scribbled on, 600told the operator which tape to mount when, 601and provided more assistance 602for the operator running 603.Xr restore 8 . 604.It 605Snapshot support is 606.Em experimental . 607Be sure you have a backup before you use it. 608.El 609