man/man8/zdb.8

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  13 .\" Copyright 2012, Richard Lowe.
  14 .\" Copyright (c) 2012 by Delphix. All rights reserved.
  15 .\"
  16 .TH "ZDB" "8" "February 15, 2012" "" ""
  17
  18 .SH "NAME"
  19 \fBzdb\fR - Display zpool debugging and consistency information
  20
  21 .SH "SYNOPSIS"
  22 \fBzdb\fR [-CumdibcsDvhLMXFPA] [-e [-p \fIpath\fR...]] [-t \fItxg\fR]
  23     [-U \fIcache\fR] [-I \fIinflight I/Os\fR]
  24     [\fIpoolname\fR [\fIobject\fR ...]]
  25
  26 .P
  27 \fBzdb\fR [-divPA] [-e [-p \fIpath\fR...]] [-U \fIcache\fR]
  28     \fIdataset\fR [\fIobject\fR ...]
  29
  30 .P
  31 \fBzdb\fR -m [-MLXFPA] [-t \fItxg\fR] [-e [-p \fIpath\fR...]] [-U \fIcache\fR]
  32     \fIpoolname\fR [\fIvdev\fR [\fImetaslab\fR ...]]
  33
  34 .P
  35 \fBzdb\fR -R [-A] [-e [-p \fIpath\fR...]] [-U \fIcache\fR] \fIpoolname\fR
  36     \fIvdev\fR:\fIoffset\fR:\fIsize\fR[:\fIflags\fR]
  37
  38 .P
  39 \fBzdb\fR -S [-AP] [-e [-p \fIpath\fR...]] [-U \fIcache\fR] \fIpoolname\fR
  40
  41 .P
  42 \fBzdb\fR -l [-uA] \fIdevice\fR
  43
  44 .P
  45 \fBzdb\fR -C [-A] [-U \fIcache\fR]
  46
  47 .SH "DESCRIPTION"
  48 The \fBzdb\fR utility displays information about a ZFS pool useful for
  49 debugging and performs some amount of consistency checking. It is a not a
  50 general purpose tool and options (and facilities) may change. This is neither
  51 a fsck(8) nor an fsdb(8) utility.
  52
  53 .P
  54 The output of this command in general reflects the on-disk structure of a ZFS
  55 pool, and is inherently unstable. The precise output of most invocations is
  56 not documented, a knowledge of ZFS internals is assumed.
  57
  58 .P
  59 If the \fIdataset\fR argument does not contain any \fB/\fR or \fB@\fR
  60 characters, it is interpreted as a pool name.  The root dataset can be
  61 specified as \fIpool\fB/\fR (pool name followed by a slash).
  62
  63 .P
  64 When operating on an imported and active pool it is possible, though unlikely,
  65 that zdb may interpret inconsistent pool data and behave erratically.
  66
  67 .SH "OPTIONS"
  68 Display options:
  69
  70 .sp
  71 .ne 2
  72 .na
  73 \fB-b\fR
  74 .ad
  75 .sp .6
  76 .RS 4n
  77 Display statistics regarding the number, size (logical, physical and
  78 allocated) and deduplication of blocks.
  79 .RE
  80
  81 .sp
  82 .ne 2
  83 .na
  84 \fB-c\fR
  85 .ad
  86 .sp .6
  87 .RS 4n
  88 Verify the checksum of all metadata blocks while printing block statistics
  89 (see \fB-b\fR).
  90 .sp
  91 If specified multiple times, verify the checksums of all blocks.
  92 .RE
  93
  94 .sp
  95 .ne 2
  96 .na
  97 \fB-C\fR
  98 .ad
  99 .sp .6
 100 .RS 4n
 101 Display information about the configuration. If specified with no other
 102 options, instead display information about the cache file
 103 (\fB/etc/zfs/zpool.cache\fR). To specify the cache file to display, see
 104 \fB-U\fR.
 105 .P
 106 If specified multiple times, and a pool name is also specified display both
 107 the cached configuration and the on-disk configuration.  If specified multiple
 108 times with \fB-e\fR also display the configuration that would be used were the
 109 pool to be imported.
 110 .RE
 111
 112 .sp
 113 .ne 2
 114 .na
 115 \fB-d\fR
 116 .ad
 117 .sp .6
 118 .RS 4n
 119 Display information about datasets. Specified once, displays basic dataset
 120 information: ID, create transaction, size, and object count.
 121 .sp
 122 If specified multiple times provides greater and greater verbosity.
 123 .sp
 124 If object IDs are specified, display information about those specific objects only.
 125 .RE
 126
 127 .sp
 128 .ne 2
 129 .na
 130 \fB-D\fR
 131 .ad
 132 .sp .6
 133 .RS 4n
 134 Display deduplication statistics, including the deduplication ratio (dedup),
 135 compression ratio (compress), inflation due to the zfs copies property
 136 (copies), and an overall effective ratio (dedup * compress / copies).
 137 .sp
 138 If specified twice, display a histogram of deduplication statistics, showing
 139 the allocated (physically present on disk) and referenced (logically
 140 referenced in the pool) block counts and sizes by reference count.
 141 .sp
 142 If specified a third time, display the statistics independently for each deduplication table.
 143 .sp
 144 If specified a fourth time, dump the contents of the deduplication tables describing duplicate blocks.
 145 .sp
 146 If specified a fifth time, also dump the contents of the deduplication tables describing unique blocks.
 147 .RE
 148
 149 .sp
 150 .ne 2
 151 .na
 152 \fB-h\fR
 153 .ad
 154 .sp .6
 155 .RS 4n
 156 Display pool history similar to \fBzpool history\fR, but include internal
 157 changes, transaction, and dataset information.
 158 .RE
 159
 160 .sp
 161 .ne 2
 162 .na
 163 \fB-i\fR
 164 .ad
 165 .sp .6
 166 .RS 4n
 167 Display information about intent log (ZIL) entries relating to each
 168 dataset. If specified multiple times, display counts of each intent log
 169 transaction type.
 170 .RE
 171
 172 .sp
 173 .ne 2
 174 .na
 175 \fB-l\fR \fIdevice\fR
 176 .ad
 177 .sp .6
 178 .RS 4n
 179 Display the vdev labels from the specified device. If the \fB-u\fR option is
 180 also specified, also display the uberblocks on this device.
 181 .RE
 182
 183 .sp
 184 .ne 2
 185 .na
 186 \fB-L\fR
 187 .ad
 188 .sp .6
 189 .RS 4n
 190 Disable leak tracing and the loading of space maps.  By default, \fBzdb\fR
 191 verifies that all non-free blocks are referenced, which can be very expensive.
 192 .RE
 193
 194 .sp
 195 .ne 2
 196 .na
 197 \fB-m\fR
 198 .ad
 199 .sp .6
 200 .RS 4n
 201 Display the offset, spacemap, and free space of each metaslab.
 202 When specified twice, also display information about the on-disk free
 203 space histogram associated with each metaslab. When specified three time,
 204 display the maximum contiguous free space, the in-core free space histogram,
 205 and the percentage of free space in each space map.  When specified
 206 four times display every spacemap record.
 207 .RE
 208
 209 .sp
 210 .ne 2
 211 .na
 212 \fB-M\fR
 213 .ad
 214 .sp .6
 215 .RS 4n
 216 Display the offset, spacemap, and free space of each metaslab.
 217 When specified twice, also display information about the maximum contiguous
 218 free space and the percentage of free space in each space map.  When specified
 219 three times display every spacemap record.
 220 .RE
 221
 222 .sp
 223 .ne 2
 224 .na
 225 \fB-R\fR \fIpoolname\fR \fIvdev\fR:\fIoffset\fR:\fIsize\fR[:\fIflags\fR]
 226 .ad
 227 .sp .6
 228 .RS 4n
 229 Read and display a block from the specified device. By default the block is
 230 displayed as a hex dump, but see the description of the \'r\' flag, below.
 231 .sp
 232 The block is specified in terms of a colon-separated tuple \fIvdev\fR (an
 233 integer vdev identifier) \fIoffset\fR (the offset within the vdev) \fIsize\fR
 234 (the size of the block to read) and, optionally, \fIflags\fR (a set of flags,
 235 described below).
 236
 237 .sp
 238 .ne 2
 239 .na
 240 \fBb\fR \fIoffset\fR
 241 .ad
 242 .sp .6
 243 .RS 4n
 244 Print block pointer
 245 .RE
 246
 247 .sp
 248 .ne 2
 249 .na
 250 \fBd\fR
 251 .ad
 252 .sp .6
 253 .RS 4n
 254 Decompress the block
 255 .RE
 256
 257 .sp
 258 .ne 2
 259 .na
 260 \fBe\fR
 261 .ad
 262 .sp .6
 263 .RS 4n
 264 Byte swap the block
 265 .RE
 266
 267 .sp
 268 .ne 2
 269 .na
 270 \fBg\fR
 271 .ad
 272 .sp .6
 273 .RS 4n
 274 Dump gang block header
 275 .RE
 276
 277 .sp
 278 .ne 2
 279 .na
 280 \fBi\fR
 281 .ad
 282 .sp .6
 283 .RS 4n
 284 Dump indirect block
 285 .RE
 286
 287 .sp
 288 .ne 2
 289 .na
 290 \fBr\fR
 291 .ad
 292 .sp .6
 293 .RS 4n
 294 Dump raw uninterpreted block data
 295 .RE
 296 .RE
 297
 298 .sp
 299 .ne 2
 300 .na
 301 \fB-s\fR
 302 .ad
 303 .sp .6
 304 .RS 4n
 305 Report statistics on \fBzdb\fR\'s I/O. Display operation counts, bandwidth,
 306 and error counts of I/O to the pool from \fBzdb\fR.
 307 .RE
 308
 309 .sp
 310 .ne 2
 311 .na
 312 \fB-S\fR
 313 .ad
 314 .sp .6
 315 .RS 4n
 316 Simulate the effects of deduplication, constructing a DDT and then display
 317 that DDT as with \fB-DD\fR.
 318 .RE
 319
 320 .sp
 321 .ne 2
 322 .na
 323 \fB-u\fR
 324 .ad
 325 .sp .6
 326 .RS 4n
 327 Display the current uberblock.
 328 .RE
 329
 330 .P
 331 Other options:
 332
 333 .sp
 334 .ne 2
 335 .na
 336 \fB-A\fR
 337 .ad
 338 .sp .6
 339 .RS 4n
 340 Do not abort should any assertion fail.
 341 .RE
 342
 343 .sp
 344 .ne 2
 345 .na
 346 \fB-AA\fR
 347 .ad
 348 .sp .6
 349 .RS 4n
 350 Enable panic recovery, certain errors which would otherwise be fatal are
 351 demoted to warnings.
 352 .RE
 353
 354 .sp
 355 .ne 2
 356 .na
 357 \fB-AAA\fR
 358 .ad
 359 .sp .6
 360 .RS 4n
 361 Do not abort if asserts fail and also enable panic recovery.
 362 .RE
 363
 364 .sp
 365 .ne 2
 366 .na
 367 \fB-e\fR [-p \fIpath\fR]...
 368 .ad
 369 .sp .6
 370 .RS 4n
 371 Operate on an exported pool, not present in \fB/etc/zfs/zpool.cache\fR. The
 372 \fB-p\fR flag specifies the path under which devices are to be searched.
 373 .RE
 374
 375 .sp
 376 .ne 2
 377 .na
 378 \fB-F\fR
 379 .ad
 380 .sp .6
 381 .RS 4n
 382 Attempt to make an unreadable pool readable by trying progressively older
 383 transactions.
 384 .RE
 385
 386 .sp
 387 .ne 2
 388 .na
 389 \fB-I \fIinflight I/Os\fR \fR
 390 .ad
 391 .sp .6
 392 .RS 4n
 393 Limit the number of outstanding checksum I/Os to the specified value. The
 394 default value is 200. This option affects the performance of the \fB-c\fR
 395 option.
 396 .RE
 397
 398 .sp
 399 .ne 2
 400 .na
 401 \fB-P\fR
 402 .ad
 403 .sp .6
 404 .RS 4n
 405 Print numbers in an unscaled form more amenable to parsing, eg. 1000000 rather
 406 than 1M.
 407 .RE
 408
 409 .sp
 410 .ne 2
 411 .na
 412 \fB-t\fR \fItransaction\fR
 413 .ad
 414 .sp .6
 415 .RS 4n
 416 Specify the highest transaction to use when searching for uberblocks. See also
 417 the \fB-u\fR and \fB-l\fR options for a means to see the available uberblocks
 418 and their associated transaction numbers.
 419 .RE
 420
 421 .sp
 422 .ne 2
 423 .na
 424 \fB-U\fR \fIcachefile\fR
 425 .ad
 426 .sp .6
 427 .RS 4n
 428 Use a cache file other than \fB/etc/zfs/zpool.cache\fR.
 429 .RE
 430
 431 .sp
 432 .ne 2
 433 .na
 434 \fB-v\fR
 435 .ad
 436 .sp .6
 437 .RS 4n
 438 Enable verbosity. Specify multiple times for increased verbosity.
 439 .RE
 440
 441 .sp
 442 .ne 2
 443 .na
 444 \fB-X\fR
 445 .ad
 446 .sp .6
 447 .RS 4n
 448 Attempt \'extreme\' transaction rewind, that is attempt the same recovery as
 449 \fB-F\fR but read transactions otherwise deemed too old.
 450 .RE
 451
 452 .sp
 453 .ne 2
 454 .na
 455 \fB-V\fR
 456 .ad
 457 .sp .6
 458 .RS 4n
 459 Attempt a verbatim import. This mimics the behavior of the kernel when loading
 460 a pool from a cachefile.
 461 .RE
 462
 463 .P
 464 Specifying a display option more than once enables verbosity for only that
 465 option, with more occurrences enabling more verbosity.
 466 .P
 467 If no options are specified, all information about the named pool will be
 468 displayed at default verbosity.
 469
 470 .SH "EXAMPLES"
 471 .LP
 472 \fBExample 1 \fRDisplay the configuration of imported pool 'rpool'
 473 .sp
 474 .in +2
 475 .nf
 476 # zdb -C rpool
 477
 478 MOS Configuration:
 479         version: 28
 480         name: 'rpool'
 481  ...
 482 .fi
 483 .in -2
 484 .sp
 485
 486 .LP
 487 \fBExample 2 \fRDisplay basic dataset information about 'rpool'
 488 .sp
 489 .in +2
 490 .nf
 491 # zdb -d rpool
 492 Dataset mos [META], ID 0, cr_txg 4, 26.9M, 1051 objects
 493 Dataset rpool/swap [ZVOL], ID 59, cr_txg 356, 486M, 2 objects
 494  ...
 495 .fi
 496 .in -2
 497 .sp
 498
 499 .LP
 500 \fBExample 3 \fRDisplay basic information about object 0
 501 in 'rpool/export/home'
 502 .sp
 503 .in +2
 504 .nf
 505 # zdb -d rpool/export/home 0
 506 Dataset rpool/export/home [ZPL], ID 137, cr_txg 1546, 32K, 8 objects
 507
 508     Object  lvl   iblk   dblk  dsize  lsize   %full  type
 509          0    7    16K    16K  15.0K    16K   25.00  DMU dnode
 510 .fi
 511 .in -2
 512 .sp
 513
 514 .LP
 515 \fBExample 4 \fRDisplay the predicted effect of enabling deduplication on 'rpool'
 516 .sp
 517 .in +2
 518 .nf
 519 # zdb -S rpool
 520 Simulated DDT histogram:
 521
 522 bucket              allocated                       referenced
 523 ______   ______________________________   ______________________________
 524 refcnt   blocks   LSIZE   PSIZE   DSIZE   blocks   LSIZE   PSIZE   DSIZE
 525 ------   ------   -----   -----   -----   ------   -----   -----   -----
 526      1     694K   27.1G   15.0G   15.0G     694K   27.1G   15.0G   15.0G
 527      2    35.0K   1.33G    699M    699M    74.7K   2.79G   1.45G   1.45G
 528  ...
 529 dedup = 1.11, compress = 1.80, copies = 1.00, dedup * compress / copies = 2.00
 530 .fi
 531 .in -2
 532 .sp
 533
 534 .SH "ENVIRONMENT VARIABLES"
 535 .TP
 536 .B "SPA_CONFIG_PATH"
 537 Override the default \fBspa_config_path\fR (\fI/etc/zfs/zpool.cache\fR) setting. If \fB-U\fR flag is specified it will override this environment variable settings once again.
 538
 539 .SH "SEE ALSO"
 540 zfs(8), zpool(8)