1.\" $NetBSD: dump_lfs.8,v 1.11 2003/08/07 10:04:15 agc 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 May 26, 2003 34.Dt DUMP_LFS 8 35.Os 36.Sh NAME 37.Nm dump_lfs , 38.Nm rdump_lfs 39.Nd filesystem backup 40.Sh SYNOPSIS 41.Nm 42.Op Fl 0123456789cnSu 43.Op Fl B Ar records 44.Op Fl b Ar blocksize 45.Op Fl d Ar density 46.Op Fl f Ar file 47.Op Fl h Ar level 48.Op Fl k Ar read blocksize 49.Op Fl L Ar label 50.Op Fl r Ar cachesize 51.Op Fl s Ar feet 52.Op Fl T Ar date 53.Ar files-to-dump 54.Nm 55.Op Fl W Li \&| Fl w 56.Pp 57.in -\n(iSu 58(The 59.Bx 4.3 60option syntax is implemented for backward compatibility, but 61is not documented here). 62.Sh DESCRIPTION 63.Nm 64examines files on a filesystem and determines which files need to 65be backed up. 66These files are copied to the given disk, tape or other storage 67medium for safe keeping (see the 68.Fl f 69option below for doing remote backups). 70A dump that is larger than the output medium is broken into 71multiple volumes. 72On most media the size is determined by writing until an 73end-of-media indication is returned. 74On media that cannot reliably return an end-of-media indication 75(such as some cartridge tape drives) 76each volume is of a fixed size; 77the actual size is determined by the tape size and density and/or 78block count options below. 79By default, the same output file name is used for each volume 80after prompting the operator to change media. 81.Pp 82.Ar files-to-dump 83is either a mountpoint of a filesystem, 84or a list of files and directories on a single filesystem to be backed 85up as a subset of the filesystem. 86In the former case, either the path to a mounted filesystem, 87or the device of an unmounted filesystem can be used. 88In the latter case, certain restrictions are placed on the backup: 89.Fl u 90is ignored, the only dump level that is supported is 91.Fl 0 , 92and all of the files must reside on the same filesystem. 93.Pp 94The following options are supported by 95.Nm : 96.Bl -tag -width Ds 97.It Fl 0\-9 98Dump levels. 99A level 0, full backup, 100guarantees the entire file system is copied 101(but see also the 102.Fl h 103option below). 104A level number above 0, 105incremental backup, 106tells dump to 107copy all files new or modified since the 108last dump of a lower level. 109The default level is 9. 110.It Fl B Ar records 111The number of kilobytes per volume, rounded 112down to a multiple of the blocksize. 113This option overrides the calculation of tape size 114based on length and density. 115.It Fl b Ar blocksize 116The number of kilobytes per dump record. 117.It Fl c 118Modify the calculation of the default density and tape size to be more 119appropriate for cartridge tapes. 120.It Fl d Ar density 121Set tape density to 122.Ar density . 123The default is 1600 Bits Per Inch (BPI). 124.It Fl f Ar file 125Write the backup to 126.Ar file ; 127.Ar file 128may be a special device file 129like 130.Pa /dev/rst0 131(a tape drive), 132.Pa /dev/rsd1c 133(a disk drive), 134an ordinary file, 135or 136.Ql Fl 137(the standard output). 138Multiple file names may be given as a single argument separated by commas. 139Each file will be used for one dump volume in the order listed; 140if the dump requires more volumes than the number of names given, 141the last file name will used for all remaining volumes after prompting 142for media changes. 143If the name of the file is of the form 144.Qq host:file , 145or 146.Qq user@host:file , 147.Nm 148writes to the named file on the remote host using 149.Xr rmt 8 . 150Note that methods more secure than 151.Xr rsh 1 152.Pq such as Xr ssh 1 153can be used to invoke 154.Xr rmt 8 155on the remote host, via the environment variable 156.Ev RCMD_CMD . 157See 158.Xr rcmd 3 159for more details. 160.It Fl h Ar level 161Honor the user 162.Qq nodump 163flag 164.Pq Dv UF_NODUMP 165only for dumps at or above the given 166.Ar level . 167The default honor level is 1, 168so that incremental backups omit such files 169but full backups retain them. 170.It Fl k Ar read blocksize 171The size in kilobyte of the read buffers, rounded up to a multiple of the 172filesystem block size. 173Default is 32k. 174.It Fl L Ar label 175The user-supplied text string 176.Ar label 177is placed into the dump header, where tools like 178.Xr restore 8 179and 180.Xr file 1 181can access it. 182Note that this label is limited 183to be at most LBLSIZE (currently 16) characters, which must include 184the terminating 185.Ql \e0 . 186.It Fl n 187Whenever 188.Nm 189requires operator attention, 190notify all operators in the group 191.Qq operator 192by means similar to a 193.Xr wall 1 . 194.It Fl r Ar cachesize 195Use that many buffers for read cache operations. 196A value of zero disables the read cache altogether, higher values 197improve read performance by reading larger data blocks from the 198disk and maintaining them in an LRU cache. 199See the 200.Fl k 201option for the size of the buffers. 202Maximum is 512, the size of the cache is 203limited to 15% of the avail RAM by default. 204.It Fl s Ar feet 205Attempt to calculate the amount of tape needed 206at a particular density. 207If this amount is exceeded, 208.Nm 209prompts for a new tape. 210It is recommended to be a bit conservative on this option. 211The default tape length is 2300 feet. 212.It Fl S 213Display an estimate of the backup size and the number of tapes 214required, and exit without actually performing the dump. 215.It Fl T Ar date 216Use the specified date as the starting time for the dump 217instead of the time determined from looking in 218.Pa /etc/dumpdates . 219The format of date is the same as that of 220.Xr ctime 3 . 221This option is useful for automated dump scripts that wish to 222dump over a specific period of time. 223The 224.Fl T 225option is mutually exclusive from the 226.Fl u 227option. 228.It Fl u 229Update the file 230.Pa /etc/dumpdates 231after a successful dump. 232The format of 233.Pa /etc/dumpdates 234is readable by people, consisting of one 235free format record per line: 236filesystem name, 237increment level 238and 239.Xr ctime 3 240format dump date. 241There may be only one entry per filesystem at each level. 242The file 243.Pa /etc/dumpdates 244may be edited to change any of the fields, 245if necessary. 246If a list of files or subdirectories is being dumped 247(as opposed to and entire filesystem), then 248.Fl u 249is ignored. 250.It Fl W 251.Nm 252tells the operator what file systems need to be dumped. 253This information is gleaned from the files 254.Pa /etc/dumpdates 255and 256.Pa /etc/fstab . 257The 258.Fl W 259option causes 260.Nm 261to print out, for each file system in 262.Pa /etc/dumpdates 263the most recent dump date and level, 264and highlights those file systems that should be dumped. 265If the 266.Fl W 267option is set, all other options are ignored, and 268.Nm 269exits immediately. 270.It Fl w 271Is like W, but prints only those filesystems which need to be dumped. 272.El 273.Pp 274If 275.Nm 276honors the 277.Qq nodump 278flag 279.Pq Dv UF_NODUMP , 280files with the 281.Qq nodump 282flag will not be backed up. 283If a directory has the 284.Qq nodump 285flag, this directory and any file or directory under it will not be backed up. 286.Pp 287.Nm 288requires operator intervention on these conditions: 289end of tape, 290end of dump, 291tape write error, 292tape open error or 293disk read error (if there are more than a threshold of 32). 294In addition to alerting all operators implied by the 295.Fl n 296option, 297.Nm 298interacts with the operator on 299.Nm Ns 's 300control terminal at times when 301.Nm 302can no longer proceed, 303or if something is grossly wrong. 304All questions 305.Nm 306poses 307.Em must 308be answered by typing 309.Qq yes 310or 311.Qq no , 312appropriately. 313.Pp 314Since making a dump involves a lot of time and effort for full dumps, 315.Nm 316checkpoints itself at the start of each tape volume. 317If writing that volume fails for some reason, 318.Nm 319will, 320with operator permission, 321restart itself from the checkpoint 322after the old tape has been rewound and removed, 323and a new tape has been mounted. 324.Pp 325.Nm 326tells the operator what is going on at periodic intervals, 327including usually low estimates of the number of blocks to write, 328the number of tapes it will take, the time to completion, and 329the time to the tape change. 330The output is verbose, 331so that others know that the terminal 332controlling 333.Nm 334is busy, 335and will be for some time. 336.Pp 337In the event of a catastrophic disk event, the time required 338to restore all the necessary backup tapes or files to disk 339can be kept to a minimum by staggering the incremental dumps. 340An efficient method of staggering incremental dumps 341to minimize the number of tapes follows: 342.Bl -bullet -offset indent 343.It 344Always start with a level 0 backup, for example: 345.Bd -literal -offset indent 346/sbin/dump -0u -f /dev/nrst1 /usr/src 347.Ed 348.Pp 349This should be done at set intervals, say once a month or once every two months, 350and on a set of fresh tapes that is saved forever. 351.It 352After a level 0, dumps of active file 353systems are taken on a daily basis, 354using a modified Tower of Hanoi algorithm, 355with this sequence of dump levels: 356.Bd -literal -offset indent 3573 2 5 4 7 6 9 8 9 9 ... 358.Ed 359.Pp 360For the daily dumps, it should be possible to use a fixed number of tapes 361for each day, used on a weekly basis. 362Each week, a level 1 dump is taken, and 363the daily Hanoi sequence repeats beginning with 3. 364For weekly dumps, another fixed set of tapes per dumped file system is 365used, also on a cyclical basis. 366.El 367.Pp 368After several months or so, the daily and weekly tapes should get 369rotated out of the dump cycle and fresh tapes brought in. 370.Pp 371If 372.Nm 373receives a 374.Dv SIGINFO 375signal 376(see the 377.Qq status 378argument of 379.Xr stty 1 ) 380whilst a backup is in progress, statistics on the amount completed, 381current transfer rate, and estimated finished time, will be written 382to the standard error output. 383.Sh ENVIRONMENT 384If the following environment variables exist, they are used by 385.Nm . 386.Bl -tag -width Fl 387.It Ev TAPE 388If no -f option was specified, 389.Nm 390will use the device specified via 391.Ev TAPE 392as the dump device. 393.Ev TAPE 394may be of the form 395.Qq tapename , 396.Qq host:tapename , 397or 398.Qq user@host:tapename . 399.It Ev RCMD_CMD 400.Nm 401will use 402.Ev RCMD_CMD 403rather than 404.Xr rsh 1 405to invoke 406.Xr rmt 8 407on the remote machine. 408.El 409.Sh FILES 410.Bl -tag -width /etc/dumpdates -compact 411.It Pa /dev/nrst0 412default tape unit to use. 413Taken from 414.Dv _PATH_DEFTAPE 415in 416.Pa /usr/include/paths.h . 417.It Pa /dev/rst* 418raw SCSI tape interface 419.It Pa /etc/dumpdates 420dump date records 421.It Pa /etc/fstab 422dump table: file systems and frequency 423.It Pa /etc/group 424to find group 425.Em operator 426.El 427.Sh DIAGNOSTICS 428Many, and verbose. 429.Pp 430.Nm 431exits with zero status on success. 432Startup errors are indicated with an exit code of 1; 433abnormal termination is indicated with an exit code of 3. 434.Sh SEE ALSO 435.Xr chflags 1 , 436.Xr rcmd 1 , 437.Xr stty 1 , 438.Xr fts 3 , 439.Xr rcmd 3 , 440.Xr st 4 , 441.Xr fstab 5 , 442.Xr environ 7 , 443.Xr restore 8 , 444.Xr rmt 8 445.Sh HISTORY 446A 447.Nm 448command appeared in 449.Nx 1.5 . 450.Sh BUGS 451Fewer than 32 read errors on the filesystem are ignored. 452.Pp 453Each reel requires a new process, so parent processes for 454reels already written just hang around until the entire tape 455is written. 456.Pp 457.Nm 458with the 459.Fl W 460or 461.Fl w 462options does not report filesystems that have never been recorded 463in 464.Pa /etc/dumpdates , 465even if listed in 466.Pa /etc/fstab . 467.Pp 468When dumping a list of files or subdirectories, access privileges are 469required to scan the directory (as this is done via the 470.Xr fts 3 471routines rather than directly accessing the filesystem). 472.Pp 473It would be nice if 474.Nm 475knew about the dump sequence, 476kept track of the tapes scribbled on, 477told the operator which tape to mount when, 478and provided more assistance 479for the operator running 480.Xr restore 8 . 481