man/man8/zdb.8

   1 '\" t
   2 .\"
   3 .\" This file and its contents are supplied under the terms of the
   4 .\" Common Development and Distribution License ("CDDL"), version 1.0.
   5 .\" You may only use this file in accordance with the terms of version
   6 .\" 1.0 of the CDDL.
   7 .\"
   8 .\" A full copy of the text of the CDDL should have accompanied this
   9 .\" source.  A copy of the CDDL is also available via the Internet at
  10 .\" http://www.illumos.org/license/CDDL.
  11 .\"
  12 .\"
  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 When operating on an imported and active pool it is possible, though unlikely,
  60 that zdb may interpret inconsistent pool data and behave erratically.
  61
  62 .SH "OPTIONS"
  63 Display options:
  64
  65 .sp
  66 .ne 2
  67 .na
  68 \fB-b\fR
  69 .ad
  70 .sp .6
  71 .RS 4n
  72 Display statistics regarding the number, size (logical, physical and
  73 allocated) and deduplication of blocks.
  74 .RE
  75
  76 .sp
  77 .ne 2
  78 .na
  79 \fB-c\fR
  80 .ad
  81 .sp .6
  82 .RS 4n
  83 Verify the checksum of all metadata blocks while printing block statistics
  84 (see \fB-b\fR).
  85 .sp
  86 If specified multiple times, verify the checksums of all blocks.
  87 .RE
  88
  89 .sp
  90 .ne 2
  91 .na
  92 \fB-C\fR
  93 .ad
  94 .sp .6
  95 .RS 4n
  96 Display information about the configuration. If specified with no other
  97 options, instead display information about the cache file
  98 (\fB/etc/zfs/zpool.cache\fR). To specify the cache file to display, see
  99 \fB-U\fR.
 100 .P
 101 If specified multiple times, and a pool name is also specified display both
 102 the cached configuration and the on-disk configuration.  If specified multiple
 103 times with \fB-e\fR also display the configuration that would be used were the
 104 pool to be imported.
 105 .RE
 106
 107 .sp
 108 .ne 2
 109 .na
 110 \fB-d\fR
 111 .ad
 112 .sp .6
 113 .RS 4n
 114 Display information about datasets. Specified once, displays basic dataset
 115 information: ID, create transaction, size, and object count.
 116 .sp
 117 If specified multiple times provides greater and greater verbosity.
 118 .sp
 119 If object IDs are specified, display information about those specific objects only.
 120 .RE
 121
 122 .sp
 123 .ne 2
 124 .na
 125 \fB-D\fR
 126 .ad
 127 .sp .6
 128 .RS 4n
 129 Display deduplication statistics, including the deduplication ratio (dedup),
 130 compression ratio (compress), inflation due to the zfs copies property
 131 (copies), and an overall effective ratio (dedup * compress / copies).
 132 .sp
 133 If specified twice, display a histogram of deduplication statistics, showing
 134 the allocated (physically present on disk) and referenced (logically
 135 referenced in the pool) block counts and sizes by reference count.
 136 .sp
 137 If specified a third time, display the statistics independently for each deduplication table.
 138 .sp
 139 If specified a fourth time, dump the contents of the deduplication tables describing duplicate blocks.
 140 .sp
 141 If specified a fifth time, also dump the contents of the deduplication tables describing unique blocks.
 142 .RE
 143
 144 .sp
 145 .ne 2
 146 .na
 147 \fB-h\fR
 148 .ad
 149 .sp .6
 150 .RS 4n
 151 Display pool history similar to \fBzpool history\fR, but include internal
 152 changes, transaction, and dataset information.
 153 .RE
 154
 155 .sp
 156 .ne 2
 157 .na
 158 \fB-i\fR
 159 .ad
 160 .sp .6
 161 .RS 4n
 162 Display information about intent log (ZIL) entries relating to each
 163 dataset. If specified multiple times, display counts of each intent log
 164 transaction type.
 165 .RE
 166
 167 .sp
 168 .ne 2
 169 .na
 170 \fB-l\fR \fIdevice\fR
 171 .ad
 172 .sp .6
 173 .RS 4n
 174 Display the vdev labels from the specified device. If the \fB-u\fR option is
 175 also specified, also display the uberblocks on this device.
 176 .RE
 177
 178 .sp
 179 .ne 2
 180 .na
 181 \fB-L\fR
 182 .ad
 183 .sp .6
 184 .RS 4n
 185 Disable leak tracing and the loading of space maps.  By default, \fBzdb\fR
 186 verifies that all non-free blocks are referenced, which can be very expensive.
 187 .RE
 188
 189 .sp
 190 .ne 2
 191 .na
 192 \fB-m\fR
 193 .ad
 194 .sp .6
 195 .RS 4n
 196 Display the offset, spacemap, and free space of each metaslab.
 197 When specified twice, also display information about the on-disk free
 198 space histogram associated with each metaslab. When specified three time,
 199 display the maximum contiguous free space, the in-core free space histogram,
 200 and the percentage of free space in each space map.  When specified
 201 four times display every spacemap record.
 202 .RE
 203
 204 .sp
 205 .ne 2
 206 .na
 207 \fB-M\fR
 208 .ad
 209 .sp .6
 210 .RS 4n
 211 Display the offset, spacemap, and free space of each metaslab.
 212 When specified twice, also display information about the maximum contiguous
 213 free space and the percentage of free space in each space map.  When specified
 214 three times display every spacemap record.
 215 .RE
 216
 217 .sp
 218 .ne 2
 219 .na
 220 \fB-R\fR \fIpoolname\fR \fIvdev\fR:\fIoffset\fR:\fIsize\fR[:\fIflags\fR]
 221 .ad
 222 .sp .6
 223 .RS 4n
 224 Read and display a block from the specified device. By default the block is
 225 displayed as a hex dump, but see the description of the \'r\' flag, below.
 226 .sp
 227 The block is specified in terms of a colon-separated tuple \fIvdev\fR (an
 228 integer vdev identifier) \fIoffset\fR (the offset within the vdev) \fIsize\fR
 229 (the size of the block to read) and, optionally, \fIflags\fR (a set of flags,
 230 described below).
 231
 232 .sp
 233 .ne 2
 234 .na
 235 \fBb\fR \fIoffset\fR
 236 .ad
 237 .sp .6
 238 .RS 4n
 239 Print block pointer
 240 .RE
 241
 242 .sp
 243 .ne 2
 244 .na
 245 \fBd\fR
 246 .ad
 247 .sp .6
 248 .RS 4n
 249 Decompress the block
 250 .RE
 251
 252 .sp
 253 .ne 2
 254 .na
 255 \fBe\fR
 256 .ad
 257 .sp .6
 258 .RS 4n
 259 Byte swap the block
 260 .RE
 261
 262 .sp
 263 .ne 2
 264 .na
 265 \fBg\fR
 266 .ad
 267 .sp .6
 268 .RS 4n
 269 Dump gang block header
 270 .RE
 271
 272 .sp
 273 .ne 2
 274 .na
 275 \fBi\fR
 276 .ad
 277 .sp .6
 278 .RS 4n
 279 Dump indirect block
 280 .RE
 281
 282 .sp
 283 .ne 2
 284 .na
 285 \fBr\fR
 286 .ad
 287 .sp .6
 288 .RS 4n
 289 Dump raw uninterpreted block data
 290 .RE
 291 .RE
 292
 293 .sp
 294 .ne 2
 295 .na
 296 \fB-s\fR
 297 .ad
 298 .sp .6
 299 .RS 4n
 300 Report statistics on \fBzdb\fR\'s I/O. Display operation counts, bandwidth,
 301 and error counts of I/O to the pool from \fBzdb\fR.
 302 .RE
 303
 304 .sp
 305 .ne 2
 306 .na
 307 \fB-S\fR
 308 .ad
 309 .sp .6
 310 .RS 4n
 311 Simulate the effects of deduplication, constructing a DDT and then display
 312 that DDT as with \fB-DD\fR.
 313 .RE
 314
 315 .sp
 316 .ne 2
 317 .na
 318 \fB-u\fR
 319 .ad
 320 .sp .6
 321 .RS 4n
 322 Display the current uberblock.
 323 .RE
 324
 325 .P
 326 Other options:
 327
 328 .sp
 329 .ne 2
 330 .na
 331 \fB-A\fR
 332 .ad
 333 .sp .6
 334 .RS 4n
 335 Do not abort should any assertion fail.
 336 .RE
 337
 338 .sp
 339 .ne 2
 340 .na
 341 \fB-AA\fR
 342 .ad
 343 .sp .6
 344 .RS 4n
 345 Enable panic recovery, certain errors which would otherwise be fatal are
 346 demoted to warnings.
 347 .RE
 348
 349 .sp
 350 .ne 2
 351 .na
 352 \fB-AAA\fR
 353 .ad
 354 .sp .6
 355 .RS 4n
 356 Do not abort if asserts fail and also enable panic recovery.
 357 .RE
 358
 359 .sp
 360 .ne 2
 361 .na
 362 \fB-e\fR [-p \fIpath\fR]...
 363 .ad
 364 .sp .6
 365 .RS 4n
 366 Operate on an exported pool, not present in \fB/etc/zfs/zpool.cache\fR. The
 367 \fB-p\fR flag specifies the path under which devices are to be searched.
 368 .RE
 369
 370 .sp
 371 .ne 2
 372 .na
 373 \fB-F\fR
 374 .ad
 375 .sp .6
 376 .RS 4n
 377 Attempt to make an unreadable pool readable by trying progressively older
 378 transactions.
 379 .RE
 380
 381 .sp
 382 .ne 2
 383 .na
 384 \fB-I \fIinflight I/Os\fR \fR
 385 .ad
 386 .sp .6
 387 .RS 4n
 388 Limit the number of outstanding checksum I/Os to the specified value. The
 389 default value is 200. This option affects the performance of the \fB-c\fR
 390 option.
 391 .RE
 392
 393 .sp
 394 .ne 2
 395 .na
 396 \fB-P\fR
 397 .ad
 398 .sp .6
 399 .RS 4n
 400 Print numbers in an unscaled form more amenable to parsing, eg. 1000000 rather
 401 than 1M.
 402 .RE
 403
 404 .sp
 405 .ne 2
 406 .na
 407 \fB-t\fR \fItransaction\fR
 408 .ad
 409 .sp .6
 410 .RS 4n
 411 Specify the highest transaction to use when searching for uberblocks. See also
 412 the \fB-u\fR and \fB-l\fR options for a means to see the available uberblocks
 413 and their associated transaction numbers.
 414 .RE
 415
 416 .sp
 417 .ne 2
 418 .na
 419 \fB-U\fR \fIcachefile\fR
 420 .ad
 421 .sp .6
 422 .RS 4n
 423 Use a cache file other than \fB/etc/zfs/zpool.cache\fR.
 424 .RE
 425
 426 .sp
 427 .ne 2
 428 .na
 429 \fB-v\fR
 430 .ad
 431 .sp .6
 432 .RS 4n
 433 Enable verbosity. Specify multiple times for increased verbosity.
 434 .RE
 435
 436 .sp
 437 .ne 2
 438 .na
 439 \fB-X\fR
 440 .ad
 441 .sp .6
 442 .RS 4n
 443 Attempt \'extreme\' transaction rewind, that is attempt the same recovery as
 444 \fB-F\fR but read transactions otherwise deemed too old.
 445 .RE
 446
 447 .sp
 448 .ne 2
 449 .na
 450 \fB-V\fR
 451 .ad
 452 .sp .6
 453 .RS 4n
 454 Attempt a verbatim import. This mimics the behavior of the kernel when loading
 455 a pool from a cachefile.
 456 .RE
 457
 458 .P
 459 Specifying a display option more than once enables verbosity for only that
 460 option, with more occurrences enabling more verbosity.
 461 .P
 462 If no options are specified, all information about the named pool will be
 463 displayed at default verbosity.
 464
 465 .SH "EXAMPLES"
 466 .LP
 467 \fBExample 1 \fRDisplay the configuration of imported pool 'rpool'
 468 .sp
 469 .in +2
 470 .nf
 471 # zdb -C rpool
 472
 473 MOS Configuration:
 474         version: 28
 475         name: 'rpool'
 476  ...
 477 .fi
 478 .in -2
 479 .sp
 480
 481 .LP
 482 \fBExample 2 \fRDisplay basic dataset information about 'rpool'
 483 .sp
 484 .in +2
 485 .nf
 486 # zdb -d rpool
 487 Dataset mos [META], ID 0, cr_txg 4, 26.9M, 1051 objects
 488 Dataset rpool/swap [ZVOL], ID 59, cr_txg 356, 486M, 2 objects
 489  ...
 490 .fi
 491 .in -2
 492 .sp
 493
 494 .LP
 495 \fBExample 3 \fRDisplay basic information about object 0
 496 in 'rpool/export/home'
 497 .sp
 498 .in +2
 499 .nf
 500 # zdb -d rpool/export/home 0
 501 Dataset rpool/export/home [ZPL], ID 137, cr_txg 1546, 32K, 8 objects
 502
 503     Object  lvl   iblk   dblk  dsize  lsize   %full  type
 504          0    7    16K    16K  15.0K    16K   25.00  DMU dnode
 505 .fi
 506 .in -2
 507 .sp
 508
 509 .LP
 510 \fBExample 4 \fRDisplay the predicted effect of enabling deduplication on 'rpool'
 511 .sp
 512 .in +2
 513 .nf
 514 # zdb -S rpool
 515 Simulated DDT histogram:
 516
 517 bucket              allocated                       referenced
 518 ______   ______________________________   ______________________________
 519 refcnt   blocks   LSIZE   PSIZE   DSIZE   blocks   LSIZE   PSIZE   DSIZE
 520 ------   ------   -----   -----   -----   ------   -----   -----   -----
 521      1     694K   27.1G   15.0G   15.0G     694K   27.1G   15.0G   15.0G
 522      2    35.0K   1.33G    699M    699M    74.7K   2.79G   1.45G   1.45G
 523  ...
 524 dedup = 1.11, compress = 1.80, copies = 1.00, dedup * compress / copies = 2.00
 525 .fi
 526 .in -2
 527 .sp
 528
 529 .SH "ENVIRONMENT VARIABLES"
 530 .TP
 531 .B "SPA_CONFIG_PATH"
 532 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.
 533
 534 .SH "SEE ALSO"
 535 zfs(8), zpool(8)