dump/dump.8

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  33 .\"     @(#)dump.8      8.3 (Berkeley) 5/1/95
  34 .\"
  35 .Dd May 1, 1995
  36 .Dt DUMP 8
  37 .Os BSD 4
  38 .Sh NAME
  39 .Nm dump
  40 .Nd filesystem backup
  41 .Sh SYNOPSIS
  42 .Nm dump
  43 .Op Fl 0123456789cnu
  44 .Op Fl B Ar records
  45 .Op Fl b Ar blocksize
  46 .Op Fl d Ar density
  47 .Op Fl f Ar file
  48 .Op Fl h Ar level
  49 .Op Fl s Ar feet
  50 .Op Fl T Ar date
  51 .Ar filesystem
  52 .Nm dump
  53 .Op Fl 0123456789cnu
  54 .Op Fl B Ar records
  55 .Op Fl b Ar blocksize
  56 .Op Fl d Ar density
  57 .Op Fl f Ar file
  58 .Op Fl h Ar level
  59 .Op Fl s Ar feet
  60 .Op Fl T Ar date
  61 .Ar directory
  62 .Nm dump
  63 .Op Fl W Li \&| Fl w
  64 .Pp
  65 .in -\\n(iSu
  66 (The
  67 .Bx 4.3
  68 option syntax is implemented for backward compatibility, but
  69 is not documented here.)
  70 .Sh DESCRIPTION
  71 .Nm Dump
  72 examines files
  73 on a filesystem
  74 and determines which files
  75 need to be backed up. These files
  76 are copied to the given disk, tape or other
  77 storage medium for safe keeping (see the
  78 .Fl f
  79 option below for doing remote backups).
  80 A dump that is larger than the output medium is broken into
  81 multiple volumes.
  82 On most media the size is determined by writing until an
  83 end-of-media indication is returned.
  84 On media that cannot reliably return an end-of-media indication
  85 (such as some cartridge tape drives)
  86 each volume is of a fixed size;
  87 the actual size is determined by the tape size and density and/or
  88 block count options below.
  89 By default, the same output file name is used for each volume
  90 after prompting the operator to change media.
  91 .Pp
  92 The following options are supported by
  93 .Nm dump :
  94 .Bl -tag -width Ds
  95 .It Fl 0\-9
  96 Dump levels.
  97 A level 0, full backup,
  98 guarantees the entire file system is copied
  99 (but see also the
 100 .Fl h
 101 option below).
 102 A level number above 0,
 103 incremental backup,
 104 tells dump to
 105 copy all files new or modified since the
 106 last dump of the same or lower level.
 107 The default level is 9.
 108 .It Fl B Ar records
 109 The number of dump records per volume.
 110 This option overrides the calculation of tape size
 111 based on length and density.
 112 .It Fl b Ar blocksize
 113 The number of kilobytes per dump record.
 114 .It Fl c
 115 Modify the calculation of the default density and tape size to be more
 116 appropriate for cartridge tapes.
 117 .It Fl d Ar density
 118 Set tape density to
 119 .Ar density .
 120 The default is 1600BPI.
 121 .It Fl f Ar file
 122 Write the backup to
 123 .Ar file ;
 124 .Ar file
 125 may be a special device file
 126 like
 127 .Pa /dev/rmt12
 128 (a tape drive),
 129 .Pa /dev/rsd1c
 130 (a disk drive),
 131 an ordinary file,
 132 or
 133 .Ql Fl
 134 (the standard output).
 135 Multiple file names may be given as a single argument separated by commas.
 136 Each file will be used for one dump volume in the order listed;
 137 if the dump requires more volumes than the number of names given,
 138 the last file name will used for all remaining volumes after prompting
 139 for media changes.
 140 If the name of the file is of the form
 141 .Dq host:file ,
 142 or
 143 .Dq user@host:file ,
 144 .Nm dump
 145 writes to the named file on the remote host using
 146 .Xr rmt 8 .
 147 .It Fl h Ar level
 148 Honor the user
 149 .Dq nodump
 150 flag
 151 .Dp Dv UF_NODUMP
 152 only for dumps at or above the given
 153 .Ar level .
 154 The default honor level is 1,
 155 so that incremental backups omit such files
 156 but full backups retain them.
 157 .It Fl n
 158 Whenever
 159 .Nm dump
 160 requires operator attention,
 161 notify all operators in the group
 162 .Dq operator
 163 by means similar to a
 164 .Xr wall 1 .
 165 .It Fl s Ar feet
 166 Attempt to calculate the amount of tape needed
 167 at a particular density.
 168 If this amount is exceeded,
 169 .Nm dump
 170 prompts for a new tape.
 171 It is recommended to be a bit conservative on this option.
 172 The default tape length is 2300 feet.
 173 .ne 1i
 174 .It Fl T Ar date
 175 Use the specified date as the starting time for the dump
 176 instead of the time determined from looking in
 177 .Pa /etc/dumpdates .
 178 The format of date is the same as that of
 179 .Xr ctime 3 .
 180 This option is useful for automated dump scripts that wish to
 181 dump over a specific period of time.
 182 The
 183 .Fl T
 184 option is mutually exclusive from the
 185 .Fl u
 186 option.
 187 .It Fl u
 188 Update the file
 189 .Pa /etc/dumpdates
 190 after a successful dump.
 191 The format of
 192 .Pa /etc/dumpdates
 193 is readable by people, consisting of one
 194 free format record per line:
 195 filesystem name,
 196 increment level
 197 and
 198 .Xr ctime 3
 199 format dump date.
 200 There may be only one entry per filesystem at each level.
 201 The file
 202 .Pa /etc/dumpdates
 203 may be edited to change any of the fields,
 204 if necessary.
 205 .It Fl W
 206 .Nm Dump
 207 tells the operator what file systems need to be dumped.
 208 This information is gleaned from the files
 209 .Pa /etc/dumpdates
 210 and
 211 .Pa /etc/fstab .
 212 The
 213 .Fl W
 214 option causes
 215 .Nm dump
 216 to print out, for each file system in
 217 .Pa /etc/dumpdates
 218 the most recent dump date and level,
 219 and highlights those file systems that should be dumped.
 220 If the
 221 .Fl W
 222 option is set, all other options are ignored, and
 223 .Nm dump
 224 exits immediately.
 225 .It Fl w
 226 Is like W, but prints only those filesystems which need to be dumped.
 227 .El
 228 .Pp
 229 .Nm Dump
 230 requires operator intervention on these conditions:
 231 end of tape,
 232 end of dump,
 233 tape write error,
 234 tape open error or
 235 disk read error (if there are more than a threshold of 32).
 236 In addition to alerting all operators implied by the
 237 .Fl n
 238 key,
 239 .Nm dump
 240 interacts with the operator on
 241 .Em dump's
 242 control terminal at times when
 243 .Nm dump
 244 can no longer proceed,
 245 or if something is grossly wrong.
 246 All questions
 247 .Nm dump
 248 poses
 249 .Em must
 250 be answered by typing
 251 .Dq yes
 252 or
 253 .Dq no ,
 254 appropriately.
 255 .Pp
 256 Since making a dump involves a lot of time and effort for full dumps,
 257 .Nm dump
 258 checkpoints itself at the start of each tape volume.
 259 If writing that volume fails for some reason,
 260 .Nm dump
 261 will,
 262 with operator permission,
 263 restart itself from the checkpoint
 264 after the old tape has been rewound and removed,
 265 and a new tape has been mounted.
 266 .Pp
 267 .Nm Dump
 268 tells the operator what is going on at periodic intervals,
 269 including usually low estimates of the number of blocks to write,
 270 the number of tapes it will take, the time to completion, and
 271 the time to the tape change.
 272 The output is verbose,
 273 so that others know that the terminal
 274 controlling
 275 .Nm dump
 276 is busy,
 277 and will be for some time.
 278 .Pp
 279 In the event of a catastrophic disk event, the time required
 280 to restore all the necessary backup tapes or files to disk
 281 can be kept to a minimum by staggering the incremental dumps.
 282 An efficient method of staggering incremental dumps
 283 to minimize the number of tapes follows:
 284 .Bl -bullet -offset indent
 285 .It
 286 Always start with a level 0 backup, for example:
 287 .Bd -literal -offset indent
 288 /sbin/dump -0u -f /dev/nrst1 /usr/src
 289 .Ed
 290 .Pp
 291 This should be done at set intervals, say once a month or once every two months,
 292 and on a set of fresh tapes that is saved forever.
 293 .It
 294 After a level 0, dumps of active file
 295 systems are taken on a daily basis,
 296 using a modified Tower of Hanoi algorithm,
 297 with this sequence of dump levels:
 298 .Bd -literal -offset indent
 299 3 2 5 4 7 6 9 8 9 9 ...
 300 .Ed
 301 .Pp
 302 For the daily dumps, it should be possible to use a fixed number of tapes
 303 for each day, used on a weekly basis.
 304 Each week, a level 1 dump is taken, and
 305 the daily Hanoi sequence repeats beginning with 3.
 306 For weekly dumps, another fixed set of tapes per dumped file system is
 307 used, also on a cyclical basis.
 308 .El
 309 .Pp
 310 After several months or so, the daily and weekly tapes should get
 311 rotated out of the dump cycle and fresh tapes brought in.
 312 .Sh FILES
 313 .Bl -tag -width /etc/dumpdates -compact
 314 .It Pa /dev/rmt8
 315 default tape unit to dump to
 316 .It Pa /etc/dumpdates
 317 dump date records
 318 .It Pa /etc/fstab
 319 dump table: file systems and frequency
 320 .It Pa /etc/group
 321 to find group
 322 .Em operator
 323 .El
 324 .Sh SEE ALSO
 325 .Xr restore 8 ,
 326 .Xr rmt 8 ,
 327 .Xr dump 5 ,
 328 .Xr fstab 5
 329 .Sh DIAGNOSTICS
 330 Many, and verbose.
 331 .Pp
 332 Dump exits with zero status on success.
 333 Startup errors are indicated with an exit code of 1;
 334 abnormal termination is indicated with an exit code of 3.
 335 .Sh BUGS
 336 Fewer than 32 read errors on the filesystem are ignored.
 337 .Pp
 338 Each reel requires a new process, so parent processes for
 339 reels already written just hang around until the entire tape
 340 is written.
 341 .Pp
 342 .Nm Dump
 343 with the
 344 .Fl W
 345 or
 346 .Fl w
 347 options does not report filesystems that have never been recorded
 348 in
 349 .Pa /etc/dumpdates ,
 350 even if listed in
 351 .Pa /etc/fstab .
 352 .Pp
 353 It would be nice if
 354 .Nm dump
 355 knew about the dump sequence,
 356 kept track of the tapes scribbled on,
 357 told the operator which tape to mount when,
 358 and provided more assistance
 359 for the operator running
 360 .Xr restore .
 361 .Sh HISTORY
 362 A
 363 .Nm dump
 364 command appeared in Version 6 AT&T UNIX.