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 .\" All Rights Reserved.
26 .Nd Display zpool debugging and consistency information
29 .Op Fl CumdibcsDvhLXFPA
30 .Op Fl e Op Fl p Ar path...
36 .Op Fl e Op Fl p Ar path...
42 .Op Fl e Op Fl p Ar path...
46 .Op Fl e Op Fl p Ar path...
48 .Ar vdev Ns : Ns Ar offset Ns : Ns Ar size Ns Op Ns : Ns Ar flags
52 .Op Fl e Op Fl p Ar path...
65 utility displays information about a ZFS pool useful for debugging and
66 performs some amount of consistency checking.
67 It is a not a general purpose tool and options (and facilities) may change.
74 The output of this command in general reflects the on-disk structure of a ZFS
75 pool, and is inherently unstable.
76 The precise output of most invocations is not documented, a knowledge of ZFS
79 When operating on an imported and active pool it is possible, though unlikely,
80 that zdb may interpret inconsistent pool data and behave erratically.
83 .Bl -tag -width indent
85 Display statistics regarding the number, size (logical, physical and
86 allocated) and deduplication of blocks.
88 Verify the checksum of all metadata blocks while printing block statistics
92 If specified multiple times, verify the checksums of all blocks.
94 Display information about the configuration. If specified with no other
95 options, instead display information about the cache file
96 .Po Pa /etc/zfs/zpool.cache Pc .
97 To specify the cache file to display, see
100 If specified multiple times, and a pool name is also specified display both
101 the cached configuration and the on-disk configuration.
102 If specified multiple times with
104 also display the configuration that would be used were the pool to be
107 Display information about datasets. Specified once, displays basic dataset
108 information: ID, create transaction, size, and object count.
110 If specified multiple times provides greater and greater verbosity.
112 If object IDs are specified, display information about those specific objects only.
114 Display deduplication statistics, including the deduplication ratio (dedup),
115 compression ratio (compress), inflation due to the zfs copies property
116 (copies), and an overall effective ratio (dedup * compress / copies).
118 If specified twice, display a histogram of deduplication statistics, showing
119 the allocated (physically present on disk) and referenced (logically
120 referenced in the pool) block counts and sizes by reference count.
122 Display pool history similar to
124 but include internal changes, transaction, and dataset information.
126 Display information about intent log (ZIL) entries relating to each
128 If specified multiple times, display counts of each intent log transaction
131 Display the vdev labels from the specified device.
134 option is also specified, also display the uberblocks on this device.
136 Disable leak tracing and the loading of space maps.
139 verifies that all non-free blocks are referenced, which can be very expensive.
141 Display the offset, spacemap, and free space of each metaslab.
142 When specified twice, also display information about the maximum contiguous
143 free space and the percentage of free space in each space map.
144 When specified three times display every spacemap record.
147 .Ar vdev Ns : Ns Ar offset Ns : Ns Ar size Ns Op Ns : Ns Ar flags
149 Read and display a block from the specified device. By default the block is
150 displayed as a hex dump, but see the description of the
154 The block is specified in terms of a colon-separated tuple
156 (an integer vdev identifier)
158 (the offset within the vdev)
160 (the size of the block to read) and, optionally,
162 (a set of flags, described below).
163 .Bl -tag -width indent
171 Dump gang block header
175 Dump raw uninterpreted block data
181 Display operation counts, bandwidth, and error counts of I/O to the pool from
184 Simulate the effects of deduplication, constructing a DDT and then display
185 that DDT as with \fB-DD\fR.
187 Display the current uberblock.
191 .Bl -tag -width indent
193 Do not abort should any assertion fail.
195 Enable panic recovery, certain errors which would otherwise be fatal are
198 Do not abort if asserts fail and also enable panic recovery.
199 .It Fl e Op Fl p Ar path...
200 Operate on an exported pool, not present in
201 .Pa /etc/zfs/zpool.cache .
204 flag specifies the path under which devices are to be searched.
206 Attempt to make an unreadable pool readable by trying progressively older
209 Print numbers in an unscaled form more amenable to parsing, eg. 1000000 rather
211 .It Fl t Ar transaction
212 Specify the highest transaction to use when searching for uberblocks.
217 options for a means to see the available uberblocks and their associated
219 .It Fl U Ar cachefile
220 Use a cache file other than
221 .Pa /etc/zfs/zpool.cache .
222 This option is only valid with
226 Specify multiple times for increased verbosity.
230 transaction rewind, that is attempt the same recovery as
232 but read transactions otherwise deemed too old.
235 Specifying a display option more than once enables verbosity for only that
236 option, with more occurrences enabling more verbosity.
238 If no options are specified, all information about the named pool will be
239 displayed at default verbosity.
242 .It Sy Example 1 Display the configuration of imported pool 'rpool'
243 .Bd -literal -offset 2n
244 .Li # Ic zdb -C rpool
251 .It Sy Example 2 Display basic dataset information about 'rpool'
252 .Bd -literal -offset 2n
253 .Li # Ic zdb -d rpool
254 Dataset mos [META], ID 0, cr_txg 4, 26.9M, 1051 objects
255 Dataset rpool/swap [ZVOL], ID 59, cr_txg 356, 486M, 2 objects
258 .It Xo Sy Example 3 Display basic information about object 0 in
259 .Sy 'rpool/export/home'
261 .Bd -literal -offset 2n
262 .Li # Ic zdb -d rpool/export/home 0
263 Dataset rpool/export/home [ZPL], ID 137, cr_txg 1546, 32K, 8 objects
265 Object lvl iblk dblk dsize lsize %full type
266 0 7 16K 16K 15.0K 16K 25.00 DMU dnode
268 .It Xo Sy Example 4 Display the predicted effect of enabling deduplication on
271 .Bd -literal -offset 2n
272 .Li # Ic zdb -S rpool
273 Simulated DDT histogram:
275 bucket allocated referenced
276 ______ ______________________________ ______________________________
277 refcnt blocks LSIZE PSIZE DSIZE blocks LSIZE PSIZE DSIZE
278 ------ ------ ----- ----- ----- ------ ----- ----- -----
279 1 694K 27.1G 15.0G 15.0G 694K 27.1G 15.0G 15.0G
280 2 35.0K 1.33G 699M 699M 74.7K 2.79G 1.45G 1.45G
282 dedup = 1.11, compress = 1.80, copies = 1.00, dedup * compress / copies = 2.00
289 This manual page is a
291 reimplementation of the
295 modified and customized for
297 and licensed under the
298 Common Development and Distribution License
303 implementation of this manual page was initially written by
304 .An Martin Matuska Aq mm@FreeBSD.org
306 .An Marcelo Araujo Aq araujo@FreeBSD.org .