2 .\" Copyright (c) 2012, Martin Matuska <mm@FreeBSD.org>.
3 .\" All Rights Reserved.
5 .\" This file and its contents are supplied under the terms of the
6 .\" Common Development and Distribution License ("CDDL"), version 1.0.
7 .\" You may only use this file in accordance with the terms of version
10 .\" A full copy of the text of the CDDL should have accompanied this
11 .\" source. A copy of the CDDL is also available via the Internet at
12 .\" http://www.illumos.org/license/CDDL.
15 .\" Copyright 2012, Richard Lowe.
16 .\" Copyright (c) 2012, Marcelo Araujo <araujo@FreeBSD.org>.
17 .\" Copyright (c) 2012 by Delphix. All rights reserved.
18 .\" All Rights Reserved.
27 .Nd Display zpool debugging and consistency information
30 .Op Fl CumdibcsDvhLXFPA
31 .Op Fl e Op Fl p Ar path...
34 .Op Fl M Ar inflight I/Os
39 .Op Fl e Op Fl p Ar path...
46 .Op Fl e Op Fl p Ar path...
51 .Op Fl e Op Fl p Ar path...
55 .Ar vdev Ns : Ns Ar offset Ns : Ns Ar size Ns Op Ns : Ns Ar flags
59 .Op Fl e Op Fl p Ar path...
74 utility displays information about a ZFS pool useful for debugging and
75 performs some amount of consistency checking.
76 It is a not a general purpose tool and options (and facilities) may change.
83 The output of this command in general reflects the on-disk structure of a ZFS
84 pool, and is inherently unstable.
85 The precise output of most invocations is not documented, a knowledge of ZFS
88 When operating on an imported and active pool it is possible, though unlikely,
89 that zdb may interpret inconsistent pool data and behave erratically.
92 .Bl -tag -width indent
94 Display statistics regarding the number, size (logical, physical and
95 allocated) and deduplication of blocks.
97 Verify the checksum of all metadata blocks while printing block statistics
101 If specified multiple times, verify the checksums of all blocks.
103 Display information about the configuration. If specified with no other
104 options, instead display information about the cache file
105 .Po Pa /etc/zfs/zpool.cache Pc .
106 To specify the cache file to display, see
109 If specified multiple times, and a pool name is also specified display both
110 the cached configuration and the on-disk configuration.
111 If specified multiple times with
113 also display the configuration that would be used were the pool to be
116 Display information about datasets. Specified once, displays basic dataset
117 information: ID, create transaction, size, and object count.
119 If specified multiple times provides greater and greater verbosity.
121 If object IDs are specified, display information about those specific objects only.
123 Display deduplication statistics, including the deduplication ratio (dedup),
124 compression ratio (compress), inflation due to the zfs copies property
125 (copies), and an overall effective ratio (dedup * compress / copies).
127 If specified twice, display a histogram of deduplication statistics, showing
128 the allocated (physically present on disk) and referenced (logically
129 referenced in the pool) block counts and sizes by reference count.
131 If specified a third time, display the statistics independently for each deduplication table.
133 If specified a fourth time, dump the contents of the deduplication tables describing duplicate blocks.
135 If specified a fifth time, also dump the contents of the deduplication tables describing unique blocks.
137 Display pool history similar to
139 but include internal changes, transaction, and dataset information.
141 Display information about intent log (ZIL) entries relating to each
143 If specified multiple times, display counts of each intent log transaction
146 Display the vdev labels from the specified device.
149 option is also specified, also display the uberblocks on this device.
151 Disable leak tracing and the loading of space maps.
154 verifies that all non-free blocks are referenced, which can be very expensive.
156 Display the offset, spacemap, and free space of each metaslab.
157 When specified twice, also display information about the maximum contiguous
158 free space and the percentage of free space in each space map.
159 When specified three times display every spacemap record.
162 .Ar vdev Ns : Ns Ar offset Ns : Ns Ar size Ns Op Ns : Ns Ar flags
164 Read and display a block from the specified device. By default the block is
165 displayed as a hex dump, but see the description of the
169 The block is specified in terms of a colon-separated tuple
171 (an integer vdev identifier)
173 (the offset within the vdev)
175 (the size of the block to read) and, optionally,
177 (a set of flags, described below).
178 .Bl -tag -width indent
186 Dump gang block header
190 Dump raw uninterpreted block data
196 Display operation counts, bandwidth, and error counts of I/O to the pool from
199 Simulate the effects of deduplication, constructing a DDT and then display
200 that DDT as with \fB-DD\fR.
202 Display the current uberblock.
206 .Bl -tag -width indent
208 Do not abort should any assertion fail.
210 Enable panic recovery, certain errors which would otherwise be fatal are
213 Do not abort if asserts fail and also enable panic recovery.
214 .It Fl e Op Fl p Ar path...
215 Operate on an exported pool, not present in
216 .Pa /etc/zfs/zpool.cache .
219 flag specifies the path under which devices are to be searched.
221 Attempt to make an unreadable pool readable by trying progressively older
223 .It Fl M Ar inflight I/Os
224 Limit the number of outstanding checksum I/Os to the specified value.
225 The default value is 200. This option affects the performance of the
229 Print numbers in an unscaled form more amenable to parsing, eg. 1000000 rather
231 .It Fl t Ar transaction
232 Specify the highest transaction to use when searching for uberblocks.
237 options for a means to see the available uberblocks and their associated
239 .It Fl U Ar cachefile
240 Use a cache file other than
241 .Pa /boot/zfs/zpool.cache .
244 Specify multiple times for increased verbosity.
248 transaction rewind, that is attempt the same recovery as
250 but read transactions otherwise deemed too old.
253 Specifying a display option more than once enables verbosity for only that
254 option, with more occurrences enabling more verbosity.
256 If no options are specified, all information about the named pool will be
257 displayed at default verbosity.
260 .It Sy Example 1 Display the configuration of imported pool 'rpool'
261 .Bd -literal -offset 2n
262 .Li # Ic zdb -C rpool
269 .It Sy Example 2 Display basic dataset information about 'rpool'
270 .Bd -literal -offset 2n
271 .Li # Ic zdb -d rpool
272 Dataset mos [META], ID 0, cr_txg 4, 26.9M, 1051 objects
273 Dataset rpool/swap [ZVOL], ID 59, cr_txg 356, 486M, 2 objects
276 .It Xo Sy Example 3 Display basic information about object 0 in
277 .Sy 'rpool/export/home'
279 .Bd -literal -offset 2n
280 .Li # Ic zdb -d rpool/export/home 0
281 Dataset rpool/export/home [ZPL], ID 137, cr_txg 1546, 32K, 8 objects
283 Object lvl iblk dblk dsize lsize %full type
284 0 7 16K 16K 15.0K 16K 25.00 DMU dnode
286 .It Xo Sy Example 4 Display the predicted effect of enabling deduplication on
289 .Bd -literal -offset 2n
290 .Li # Ic zdb -S rpool
291 Simulated DDT histogram:
293 bucket allocated referenced
294 ______ ______________________________ ______________________________
295 refcnt blocks LSIZE PSIZE DSIZE blocks LSIZE PSIZE DSIZE
296 ------ ------ ----- ----- ----- ------ ----- ----- -----
297 1 694K 27.1G 15.0G 15.0G 694K 27.1G 15.0G 15.0G
298 2 35.0K 1.33G 699M 699M 74.7K 2.79G 1.45G 1.45G
300 dedup = 1.11, compress = 1.80, copies = 1.00, dedup * compress / copies = 2.00
307 This manual page is a
309 reimplementation of the
313 modified and customized for
315 and licensed under the
316 Common Development and Distribution License
321 implementation of this manual page was initially written by
322 .An Martin Matuska Aq mm@FreeBSD.org
324 .An Marcelo Araujo Aq araujo@FreeBSD.org .