1.\" $NetBSD: dump_lfs.8,v 1.1 1999/09/29 04:57:49 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. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)dump.8 8.3 (Berkeley) 5/1/95 36.\" 37.Dd September 3, 1999 38.Dt DUMP_LFS 8 39.Os BSD 4 40.Sh NAME 41.Nm dump_lfs , 42.Nm rdump_lfs 43.Nd filesystem backup 44.Sh SYNOPSIS 45.Nm "" 46.Op Fl 0123456789cnSu 47.Op Fl B Ar records 48.Op Fl b Ar blocksize 49.Op Fl d Ar density 50.Op Fl f Ar file 51.Op Fl h Ar level 52.Op Fl k Ar read blocksize 53.Op Fl L Ar label 54.Op Fl r Ar cachesize 55.Op Fl s Ar feet 56.Op Fl T Ar date 57.Ar files-to-dump 58.Nm "" 59.Op Fl W Li \&| Fl w 60.Pp 61.in -\\n(iSu 62(The 63.Bx 4.3 64option syntax is implemented for backward compatibility, but 65is not documented here). 66.Sh DESCRIPTION 67.Nm 68examines files on a filesystem and determines which files need to 69be backed up. 70These files are copied to the given disk, tape or other storage 71medium for safe keeping (see the 72.Fl f 73option below for doing remote backups). 74A dump that is larger than the output medium is broken into 75multiple volumes. 76On most media the size is determined by writing until an 77end-of-media indication is returned. 78On media that cannot reliably return an end-of-media indication 79(such as some cartridge tape drives) 80each volume is of a fixed size; 81the actual size is determined by the tape size and density and/or 82block count options below. 83By default, the same output file name is used for each volume 84after prompting the operator to change media. 85.Pp 86.Ar files-to-dump 87is either a mountpoint of a filesystem, 88or a list of files and directories on a single filesystem to be backed 89up as a subset of the filesystem. 90In the former case, either the path to a mounted filesystem, 91or the device of an unmounted filesystem can be used. 92In the latter case, certain restrictions are placed on the backup: 93.Fl u 94is ignored, the only dump level that is supported is 95.Fl 0 , 96and all of the files must reside on the same filesystem. 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 a lower level. 113The default level is 9. 114.It Fl B Ar records 115The number of kilobytes per volume, rounded 116down to a multiple of the blocksize. 117This option overrides the calculation of tape size 118based on length and density. 119.It Fl b Ar blocksize 120The number of kilobytes per dump record. 121.It Fl c 122Modify the calculation of the default density and tape size to be more 123appropriate for cartridge tapes. 124.It Fl d Ar density 125Set tape density to 126.Ar density . 127The default is 1600 Bits Per Inch (BPI). 128.It Fl f Ar file 129Write the backup to 130.Ar file ; 131.Ar file 132may be a special device file 133like 134.Pa /dev/rst0 135(a tape drive), 136.Pa /dev/rsd1c 137(a disk drive), 138an ordinary file, 139or 140.Ql Fl 141(the standard output). 142Multiple file names may be given as a single argument separated by commas. 143Each file will be used for one dump volume in the order listed; 144if the dump requires more volumes than the number of names given, 145the last file name will used for all remaining volumes after prompting 146for media changes. 147If the name of the file is of the form 148.Qq host:file , 149or 150.Qq user@host:file , 151.Nm 152writes to the named file on the remote host using 153.Xr rmt 8 . 154Note that methods more secure than 155.Xr rsh 1 156.Pq such as Xr ssh 1 157can be used to invoke 158.Xr rmt 8 159on the remote host, via the environment variable 160.Ev RCMD_CMD . 161See 162.Xr rcmd 3 163for more details. 164 165.It Fl h Ar level 166Honor the user 167.Qq nodump 168flag 169.Dp Dv UF_NODUMP 170only for dumps at or above the given 171.Ar level . 172The default honor level is 1, 173so that incremental backups omit such files 174but full backups retain them. 175.It Fl k Ar read blocksize 176The size in kilobyte of the read buffers, rounded up to a multiple of the 177filesystem block size. Default is 32k. 178.It Fl L Ar label 179The user-supplied text string 180.Ar label 181is placed into the dump header, where tools like 182.Xr restore 8 183and 184.Xr file 1 185can access it. 186Note that this label is limited 187to be at most LBLSIZE (currently 16) characters, which must include 188the terminating 189.Ql \e0 . 190.It Fl n 191Whenever 192.Nm 193requires operator attention, 194notify all operators in the group 195.Qq operator 196by means similar to a 197.Xr wall 1 . 198.It Fl r Ar cachesize 199Use that many buffers for read cache operations. 200A value of zero disables the read cache altogether, higher values 201improve read performance by reading larger data blocks from the 202disk and maintaining them in an LRU cache. See the 203.Fl k 204option for the size of the buffers. Maximum is 512, the size of the cache is 205limited to 15% of the avail RAM by default. 206.It Fl s Ar feet 207Attempt to calculate the amount of tape needed 208at a particular density. 209If this amount is exceeded, 210.Nm 211prompts for a new tape. 212It is recommended to be a bit conservative on this option. 213The default tape length is 2300 feet. 214.It Fl S 215Display an estimate of the backup size and the number of tapes 216required, and exit without actually performing the dump. 217.It Fl T Ar date 218Use the specified date as the starting time for the dump 219instead of the time determined from looking in 220.Pa /etc/dumpdates . 221The format of date is the same as that of 222.Xr ctime 3 . 223This option is useful for automated dump scripts that wish to 224dump over a specific period of time. 225The 226.Fl T 227option is mutually exclusive from the 228.Fl u 229option. 230.It Fl u 231Update the file 232.Pa /etc/dumpdates 233after a successful dump. 234The format of 235.Pa /etc/dumpdates 236is readable by people, consisting of one 237free format record per line: 238filesystem name, 239increment level 240and 241.Xr ctime 3 242format dump date. 243There may be only one entry per filesystem at each level. 244The file 245.Pa /etc/dumpdates 246may be edited to change any of the fields, 247if necessary. 248If a list of files or subdirectories is being dumped 249(as opposed to and entire filesystem), then 250.Fl u 251is ignored. 252.It Fl W 253.Nm 254tells the operator what file systems need to be dumped. 255This information is gleaned from the files 256.Pa /etc/dumpdates 257and 258.Pa /etc/fstab . 259The 260.Fl W 261option causes 262.Nm 263to print out, for each file system in 264.Pa /etc/dumpdates 265the most recent dump date and level, 266and highlights those file systems that should be dumped. 267If the 268.Fl W 269option is set, all other options are ignored, and 270.Nm 271exits immediately. 272.It Fl w 273Is like W, but prints only those filesystems which need to be dumped. 274.El 275.Pp 276If 277.Nm 278honors the 279.Qq nodump 280flag, 281.Dp Dv UF_NODUMP 282files with the 283.Qq nodump 284flag will not be backed up. If a directory has the 285.Qq nodump 286flag, this directory and any file or directory under it will not be backed up. 287.Pp 288.Nm 289requires operator intervention on these conditions: 290end of tape, 291end of dump, 292tape write error, 293tape open error or 294disk read error (if there are more than a threshold of 32). 295In addition to alerting all operators implied by the 296.Fl n 297option, 298.Nm 299interacts with the operator on 300.Nm "" Ns 's 301control terminal at times when 302.Nm 303can no longer proceed, 304or if something is grossly wrong. 305All questions 306.Nm 307poses 308.Em must 309be answered by typing 310.Qq yes 311or 312.Qq no , 313appropriately. 314.Pp 315Since making a dump involves a lot of time and effort for full dumps, 316.Nm 317checkpoints itself at the start of each tape volume. 318If writing that volume fails for some reason, 319.Nm 320will, 321with operator permission, 322restart itself from the checkpoint 323after the old tape has been rewound and removed, 324and a new tape has been mounted. 325.Pp 326.Nm 327tells the operator what is going on at periodic intervals, 328including usually low estimates of the number of blocks to write, 329the number of tapes it will take, the time to completion, and 330the time to the tape change. 331The output is verbose, 332so that others know that the terminal 333controlling 334.Nm 335is busy, 336and will be for some time. 337.Pp 338In the event of a catastrophic disk event, the time required 339to restore all the necessary backup tapes or files to disk 340can be kept to a minimum by staggering the incremental dumps. 341An efficient method of staggering incremental dumps 342to minimize the number of tapes follows: 343.Bl -bullet -offset indent 344.It 345Always start with a level 0 backup, for example: 346.Bd -literal -offset indent 347/sbin/dump -0u -f /dev/nrst1 /usr/src 348.Ed 349.Pp 350This should be done at set intervals, say once a month or once every two months, 351and on a set of fresh tapes that is saved forever. 352.It 353After a level 0, dumps of active file 354systems are taken on a daily basis, 355using a modified Tower of Hanoi algorithm, 356with this sequence of dump levels: 357.Bd -literal -offset indent 3583 2 5 4 7 6 9 8 9 9 ... 359.Ed 360.Pp 361For the daily dumps, it should be possible to use a fixed number of tapes 362for each day, used on a weekly basis. 363Each week, a level 1 dump is taken, and 364the daily Hanoi sequence repeats beginning with 3. 365For weekly dumps, another fixed set of tapes per dumped file system is 366used, also on a cyclical basis. 367.El 368.Pp 369After several months or so, the daily and weekly tapes should get 370rotated out of the dump cycle and fresh tapes brought in. 371.Pp 372If 373.Nm 374receives a 375.Dv SIGINFO 376signal 377(see the 378.Qq status 379argument of 380.Xr stty 1 ) 381whilst a backup is in progress, statistics on the amount completed, 382current transfer rate, and estimated finished time, will be written 383to the standard error output. 384.Sh ENVIRONMENT 385If the following environment variables exist, they are utilized by 386.Nm "" . 387.Bl -tag -width Fl 388.It Ev TAPE 389If no -f option was specified, 390.Nm 391will use the device specified via 392.Ev TAPE 393as the dump device. 394.Ev TAPE 395may be of the form 396.Qq tapename , 397.Qq host:tapename , 398or 399.Qq user@host:tapename . 400.It Ev RCMD_CMD 401.Nm 402will use 403.Ev RCMD_CMD 404rather than 405.Xr rsh 1 406to invoke 407.Xr rmt 8 408on the remote machine. 409.El 410.Sh FILES 411.Bl -tag -width /etc/dumpdates -compact 412.It Pa /dev/nrst0 413default tape unit to use. Taken 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 SEE ALSO 428.Xr chflags 1 , 429.Xr stty 1 , 430.Xr fts 3 , 431.Xr fstab 5 , 432.Xr restore 8 , 433.Xr rmt 8 , 434.Xr st 4 435.Sh DIAGNOSTICS 436Many, and verbose. 437.Pp 438.Nm 439exits with zero status on success. 440Startup errors are indicated with an exit code of 1; 441abnormal termination is indicated with an exit code of 3. 442.Sh BUGS 443Fewer than 32 read errors on the filesystem are ignored. 444.Pp 445Each reel requires a new process, so parent processes for 446reels already written just hang around until the entire tape 447is written. 448.Pp 449.Nm 450with the 451.Fl W 452or 453.Fl w 454options does not report filesystems that have never been recorded 455in 456.Pa /etc/dumpdates , 457even if listed in 458.Pa /etc/fstab . 459.Pp 460When dumping a list of files or subdirectories, access privileges are 461required to scan the directory (as this is done via the 462.Xr fts 3 463routines rather than directly accessing the filesystem). 464.Pp 465It would be nice if 466.Nm 467knew about the dump sequence, 468kept track of the tapes scribbled on, 469told the operator which tape to mount when, 470and provided more assistance 471for the operator running 472.Xr restore 8 . 473.Sh HISTORY 474A 475.Nm 476command appeared in 477.Nx 1.5. 478