1.\" 2.\" This file and its contents are supplied under the terms of the 3.\" Common Development and Distribution License ("CDDL"), version 1.0. 4.\" You may only use this file in accordance with the terms of version 5.\" 1.0 of the CDDL. 6.\" 7.\" A full copy of the text of the CDDL should have accompanied this 8.\" source. A copy of the CDDL is also available via the Internet at 9.\" http://www.illumos.org/license/CDDL. 10.\" 11.\" 12.\" Copyright 2012, Richard Lowe. 13.\" Copyright (c) 2012, 2018 by Delphix. All rights reserved. 14.\" Copyright 2017 Nexenta Systems, Inc. 15.\" 16.Dd April 14, 2017 17.Dt ZDB 8 18.Os 19.Sh NAME 20.Nm zdb 21.Nd display zpool debugging and consistency information 22.Sh SYNOPSIS 23.Nm 24.Op Fl AbcdDFGhikLMPsvX 25.Op Fl e Oo Fl V Oc Op Fl p Ar path ... 26.Op Fl I Ar inflight I/Os 27.Oo Fl o Ar var Ns = Ns Ar value Oc Ns ... 28.Op Fl t Ar txg 29.Op Fl U Ar cache 30.Op Fl x Ar dumpdir 31.Op Ar poolname Op Ar object ... 32.Nm 33.Op Fl AdiPv 34.Op Fl e Oo Fl V Oc Op Fl p Ar path ... 35.Op Fl U Ar cache 36.Ar dataset Op Ar object ... 37.Nm 38.Fl C 39.Op Fl A 40.Op Fl U Ar cache 41.Nm 42.Fl E 43.Op Fl A 44.Ar word0 Ns \&: Ns Ar word1 Ns :...: Ns Ar word15 45.Nm 46.Fl l 47.Op Fl Aqu 48.Ar device 49.Nm 50.Fl m 51.Op Fl AFLPX 52.Op Fl e Oo Fl V Oc Op Fl p Ar path ... 53.Op Fl t Ar txg 54.Op Fl U Ar cache 55.Ar poolname Op Ar vdev Op Ar metaslab ... 56.Nm 57.Fl O 58.Ar dataset path 59.Nm 60.Fl R 61.Op Fl A 62.Op Fl e Oo Fl V Oc Op Fl p Ar path ... 63.Op Fl U Ar cache 64.Ar poolname vdev Ns \&: Ns Ar offset Ns \&: Ns Ar size Ns Op : Ns Ar flags 65.Nm 66.Fl S 67.Op Fl AP 68.Op Fl e Oo Fl V Oc Op Fl p Ar path ... 69.Op Fl U Ar cache 70.Ar poolname 71.Sh DESCRIPTION 72The 73.Nm 74utility displays information about a ZFS pool useful for debugging and performs 75some amount of consistency checking. 76It is a not a general purpose tool and options 77.Pq and facilities 78may change. 79This is neither a 80.Xr fsck 8 81nor an 82.Xr fsdb 8 83utility. 84.Pp 85The output of this command in general reflects the on-disk structure of a ZFS 86pool, and is inherently unstable. 87The precise output of most invocations is not documented, a knowledge of ZFS 88internals is assumed. 89.Pp 90If the 91.Ar dataset 92argument does not contain any 93.Qq Sy / 94or 95.Qq Sy @ 96characters, it is interpreted as a pool name. 97The root dataset can be specified as 98.Ar pool Ns / 99.Pq pool name followed by a slash . 100.Pp 101When operating on an imported and active pool it is possible, though unlikely, 102that zdb may interpret inconsistent pool data and behave erratically. 103.Sh OPTIONS 104Display options: 105.Bl -tag -width Ds 106.It Fl b 107Display statistics regarding the number, size 108.Pq logical, physical and allocated 109and deduplication of blocks. 110.It Fl c 111Verify the checksum of all metadata blocks while printing block statistics 112.Po see 113.Fl b 114.Pc . 115.Pp 116If specified multiple times, verify the checksums of all blocks. 117.It Fl C 118Display information about the configuration. 119If specified with no other options, instead display information about the cache 120file 121.Pq Pa /etc/zfs/zpool.cache . 122To specify the cache file to display, see 123.Fl U . 124.Pp 125If specified multiple times, and a pool name is also specified display both the 126cached configuration and the on-disk configuration. 127If specified multiple times with 128.Fl e 129also display the configuration that would be used were the pool to be imported. 130.It Fl d 131Display information about datasets. 132Specified once, displays basic dataset information: ID, create transaction, 133size, and object count. 134.Pp 135If specified multiple times provides greater and greater verbosity. 136.Pp 137If object IDs are specified, display information about those specific objects 138only. 139.It Fl D 140Display deduplication statistics, including the deduplication ratio 141.Pq Sy dedup , 142compression ratio 143.Pq Sy compress , 144inflation due to the zfs copies property 145.Pq Sy copies , 146and an overall effective ratio 147.Pq Sy dedup No * Sy compress No / Sy copies . 148.It Fl DD 149Display a histogram of deduplication statistics, showing the allocated 150.Pq physically present on disk 151and referenced 152.Pq logically referenced in the pool 153block counts and sizes by reference count. 154.It Fl DDD 155Display the statistics independently for each deduplication table. 156.It Fl DDDD 157Dump the contents of the deduplication tables describing duplicate blocks. 158.It Fl DDDDD 159Also dump the contents of the deduplication tables describing unique blocks. 160.It Fl E Ar word0 Ns \&: Ns Ar word1 Ns :...: Ns Ar word15 161Decode and display block from an embedded block pointer specified by the 162.Ar word 163arguments. 164.It Fl h 165Display pool history similar to 166.Nm zpool Cm history , 167but include internal changes, transaction, and dataset information. 168.It Fl i 169Display information about intent log 170.Pq ZIL 171entries relating to each dataset. 172If specified multiple times, display counts of each intent log transaction type. 173.It Fl k 174Examine the checkpointed state of the pool. 175Note, the on disk format of the pool is not reverted to the checkpointed state. 176.It Fl l Ar device 177Read the vdev labels and L2ARC header from the specified device. 178.Nm Fl l 179will return 0 if valid label was found, 1 if error occurred, and 2 if no valid 180labels were found. 181The presence of L2ARC header is indicated by a specific 182sequence (L2ARC_DEV_HDR_MAGIC). 183If there is an accounting error in the size or the number of L2ARC log blocks 184.Nm Fl l 185will return 1. 186Each unique configuration is displayed only once. 187.It Fl ll Ar device 188In addition display label space usage stats. 189If a valid L2ARC header was found also display the properties of log blocks 190used for restoring L2ARC contents (persistent L2ARC). 191.It Fl lll Ar device 192Display every configuration, unique or not. 193If a valid L2ARC header was found also display the properties of log entries in 194log blocks used for restoring L2ARC contents (persistent L2ARC). 195.Pp 196If the 197.Fl q 198option is also specified, don't print the labels or the L2ARC header. 199.Pp 200If the 201.Fl u 202option is also specified, also display the uberblocks on this device. 203Specify multiple times to increase verbosity. 204.It Fl L 205Disable leak detection and the loading of space maps. 206By default, 207.Nm 208verifies that all non-free blocks are referenced, which can be very expensive. 209.It Fl m 210Display the offset, spacemap, free space of each metaslab, all the log 211spacemaps and their obsolete entry statistics. 212.It Fl mm 213Also display information about the on-disk free space histogram associated with 214each metaslab. 215.It Fl mmm 216Display the maximum contiguous free space, the in-core free space histogram, and 217the percentage of free space in each space map. 218.It Fl mmmm 219Display every spacemap record. 220.It Fl M 221Display the offset, spacemap, and free space of each metaslab. 222.It Fl MM 223Also display information about the maximum contiguous free space and the 224percentage of free space in each space map. 225.It Fl MMM 226Display every spacemap record. 227.It Fl O Ar dataset path 228Look up the specified 229.Ar path 230inside of the 231.Ar dataset 232and display its metadata and indirect blocks. 233Specified 234.Ar path 235must be relative to the root of 236.Ar dataset . 237This option can be combined with 238.Fl v 239for increasing verbosity. 240.It Xo 241.Fl R Ar poolname vdev Ns \&: Ns Ar offset Ns \&: Ns Ar size Ns Op : Ns Ar flags 242.Xc 243Read and display a block from the specified device. 244By default the block is displayed as a hex dump, but see the description of the 245.Sy r 246flag, below. 247.Pp 248The block is specified in terms of a colon-separated tuple 249.Ar vdev 250.Pq an integer vdev identifier 251.Ar offset 252.Pq the offset within the vdev 253.Ar size 254.Pq the size of the block to read 255and, optionally, 256.Ar flags 257.Pq a set of flags, described below . 258.Pp 259.Bl -tag -compact -width "b offset" 260.It Sy b Ar offset 261Print block pointer 262.It Sy d 263Decompress the block 264.It Sy e 265Byte swap the block 266.It Sy g 267Dump gang block header 268.It Sy i 269Dump indirect block 270.It Sy r 271Dump raw uninterpreted block data 272.El 273.It Fl s 274Report statistics on 275.Nm zdb 276I/O. 277Display operation counts, bandwidth, and error counts of I/O to the pool from 278.Nm . 279.It Fl S 280Simulate the effects of deduplication, constructing a DDT and then display 281that DDT as with 282.Fl DD . 283.It Fl u 284Display the current uberblock. 285.El 286.Pp 287Other options: 288.Bl -tag -width Ds 289.It Fl A 290Do not abort should any assertion fail. 291.It Fl AA 292Enable panic recovery, certain errors which would otherwise be fatal are 293demoted to warnings. 294.It Fl AAA 295Do not abort if asserts fail and also enable panic recovery. 296.It Fl e Op Fl p Ar path ... 297Operate on an exported pool, not present in 298.Pa /etc/zfs/zpool.cache . 299The 300.Fl p 301flag specifies the path under which devices are to be searched. 302.It Fl x Ar dumpdir 303All blocks accessed will be copied to files in the specified directory. 304The blocks will be placed in sparse files whose name is the same as 305that of the file or device read. 306.Nm 307can be then run on the generated files. 308Note that the 309.Fl bbc 310flags are sufficient to access 311.Pq and thus copy 312all metadata on the pool. 313.It Fl F 314Attempt to make an unreadable pool readable by trying progressively older 315transactions. 316.It Fl G 317Dump the contents of the zfs_dbgmsg buffer before exiting 318.Nm . 319zfs_dbgmsg is a buffer used by ZFS to dump advanced debug information. 320.It Fl I Ar inflight I/Os 321Limit the number of outstanding checksum I/Os to the specified value. 322The default value is 200. 323This option affects the performance of the 324.Fl c 325option. 326.It Fl o Ar var Ns = Ns Ar value ... 327Set the given global libzpool variable to the provided value. 328The value must be an unsigned 32-bit integer. 329Currently only little-endian systems are supported to avoid accidentally setting 330the high 32 bits of 64-bit variables. 331.It Fl P 332Print numbers in an unscaled form more amenable to parsing, eg. 1000000 rather 333than 1M. 334.It Fl t Ar transaction 335Specify the highest transaction to use when searching for uberblocks. 336See also the 337.Fl u 338and 339.Fl l 340options for a means to see the available uberblocks and their associated 341transaction numbers. 342.It Fl U Ar cachefile 343Use a cache file other than 344.Pa /etc/zfs/zpool.cache . 345.It Fl v 346Enable verbosity. 347Specify multiple times for increased verbosity. 348.It Fl V 349Attempt verbatim import. 350This mimics the behavior of the kernel when loading a pool from a cachefile. 351Only usable with 352.Fl e . 353.It Fl X 354Attempt 355.Qq extreme 356transaction rewind, that is attempt the same recovery as 357.Fl F 358but read transactions otherwise deemed too old. 359.El 360.Pp 361Specifying a display option more than once enables verbosity for only that 362option, with more occurrences enabling more verbosity. 363.Pp 364If no options are specified, all information about the named pool will be 365displayed at default verbosity. 366.Sh EXAMPLES 367.Bl -tag -width Ds 368.It Xo 369.Sy Example 1 370Display the configuration of imported pool 371.Pa rpool 372.Xc 373.Bd -literal 374# zdb -C rpool 375 376MOS Configuration: 377 version: 28 378 name: 'rpool' 379 ... 380.Ed 381.It Xo 382.Sy Example 2 383Display basic dataset information about 384.Pa rpool 385.Xc 386.Bd -literal 387# zdb -d rpool 388Dataset mos [META], ID 0, cr_txg 4, 26.9M, 1051 objects 389Dataset rpool/swap [ZVOL], ID 59, cr_txg 356, 486M, 2 objects 390 ... 391.Ed 392.It Xo 393.Sy Example 3 394Display basic information about object 0 in 395.Pa rpool/export/home 396.Xc 397.Bd -literal 398# zdb -d rpool/export/home 0 399Dataset rpool/export/home [ZPL], ID 137, cr_txg 1546, 32K, 8 objects 400 401 Object lvl iblk dblk dsize lsize %full type 402 0 7 16K 16K 15.0K 16K 25.00 DMU dnode 403.Ed 404.It Xo 405.Sy Example 4 406Display the predicted effect of enabling deduplication on 407.Pa rpool 408.Xc 409.Bd -literal 410# zdb -S rpool 411Simulated DDT histogram: 412 413bucket allocated referenced 414______ ______________________________ ______________________________ 415refcnt blocks LSIZE PSIZE DSIZE blocks LSIZE PSIZE DSIZE 416------ ------ ----- ----- ----- ------ ----- ----- ----- 417 1 694K 27.1G 15.0G 15.0G 694K 27.1G 15.0G 15.0G 418 2 35.0K 1.33G 699M 699M 74.7K 2.79G 1.45G 1.45G 419 ... 420dedup = 1.11, compress = 1.80, copies = 1.00, dedup * compress / copies = 2.00 421.Ed 422.El 423.Sh SEE ALSO 424.Xr zfs 8 , 425.Xr zpool 8 426