9867e8be2a
4891 want zdb option to dump all metadata Reviewed by: Sonu Pillai <sonu.pillai@delphix.com> Reviewed by: George Wilson <george.wilson@delphix.com> Reviewed by: Christopher Siden <christopher.siden@delphix.com> Reviewed by: Dan McDonald <danmcd@omniti.com> Reviewed by: Richard Lowe <richlowe@richlowe.net> Approved by: Garrett D'Amore <garrett@damore.org> We'd like a way for zdb to dump metadata in a machine-readable format, so that we can bring that back from a customer site for in-house diagnosis. Think of it as a crash dump for zpools, which can be used for post-mortem analysis of a malfunctioning pool References: https://www.illumos.org/issues/4891 https://github.com/illumos/illumos-gate/commit/df15e41 Porting notes: - [cmd/zdb/zdb.c] -a5778eazdb: Introduce -V for verbatim import - In main() getopt 'opt' variable removed and the code was brought back in line with illumos. - [lib/libzpool/kernel.c] -1e33ac1Fix Solaris thread dependency by using pthreads -f0e324fUpdate utsname support -4d58b69Fix vn_open/vn_rdwr error handling - In vn_open() allocate 'dumppath' on heap instead of stack - Properly handle 'dump_fd == -1' error path - Free 'realpath' after added vn_dumpdir_code block Ported-by: kernelOfTruth kerneloftruth@gmail.com Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
555 lines
11 KiB
Groff
555 lines
11 KiB
Groff
'\" t
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.\"
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.\" This file and its contents are supplied under the terms of the
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.\" Common Development and Distribution License ("CDDL"), version 1.0.
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.\" You may only use this file in accordance with the terms of version
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.\" 1.0 of the CDDL.
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.\"
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.\" A full copy of the text of the CDDL should have accompanied this
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.\" source. A copy of the CDDL is also available via the Internet at
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.\" http://www.illumos.org/license/CDDL.
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.\"
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.\"
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.\" Copyright 2012, Richard Lowe.
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.\" Copyright (c) 2012, 2014 by Delphix. All rights reserved.
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.\"
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.TH "ZDB" "8" "February 15, 2012" "" ""
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.SH "NAME"
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\fBzdb\fR - Display zpool debugging and consistency information
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.SH "SYNOPSIS"
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\fBzdb\fR [-CumdibcsDvhLMXFPA] [-e [-p \fIpath\fR...]] [-t \fItxg\fR]
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[-U \fIcache\fR] [-I \fIinflight I/Os\fR] [-x \fIdumpdir\fR]
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[\fIpoolname\fR [\fIobject\fR ...]]
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.P
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\fBzdb\fR [-divPA] [-e [-p \fIpath\fR...]] [-U \fIcache\fR]
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\fIdataset\fR [\fIobject\fR ...]
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.P
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\fBzdb\fR -m [-MLXFPA] [-t \fItxg\fR] [-e [-p \fIpath\fR...]] [-U \fIcache\fR]
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\fIpoolname\fR [\fIvdev\fR [\fImetaslab\fR ...]]
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.P
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\fBzdb\fR -R [-A] [-e [-p \fIpath\fR...]] [-U \fIcache\fR] \fIpoolname\fR
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\fIvdev\fR:\fIoffset\fR:\fIsize\fR[:\fIflags\fR]
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.P
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\fBzdb\fR -S [-AP] [-e [-p \fIpath\fR...]] [-U \fIcache\fR] \fIpoolname\fR
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.P
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\fBzdb\fR -l [-uA] \fIdevice\fR
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.P
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\fBzdb\fR -C [-A] [-U \fIcache\fR]
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.SH "DESCRIPTION"
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The \fBzdb\fR utility displays information about a ZFS pool useful for
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debugging and performs some amount of consistency checking. It is a not a
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general purpose tool and options (and facilities) may change. This is neither
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a fsck(8) nor an fsdb(8) utility.
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.P
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The output of this command in general reflects the on-disk structure of a ZFS
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pool, and is inherently unstable. The precise output of most invocations is
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not documented, a knowledge of ZFS internals is assumed.
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.P
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If the \fIdataset\fR argument does not contain any \fB/\fR or \fB@\fR
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characters, it is interpreted as a pool name. The root dataset can be
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specified as \fIpool\fB/\fR (pool name followed by a slash).
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.P
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When operating on an imported and active pool it is possible, though unlikely,
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that zdb may interpret inconsistent pool data and behave erratically.
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.SH "OPTIONS"
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Display options:
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.sp
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.ne 2
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.na
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\fB-b\fR
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.ad
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.sp .6
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.RS 4n
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Display statistics regarding the number, size (logical, physical and
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allocated) and deduplication of blocks.
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.RE
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.sp
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.ne 2
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.na
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\fB-c\fR
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.ad
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.sp .6
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.RS 4n
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Verify the checksum of all metadata blocks while printing block statistics
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(see \fB-b\fR).
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.sp
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If specified multiple times, verify the checksums of all blocks.
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.RE
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.sp
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.ne 2
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.na
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\fB-C\fR
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.ad
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.sp .6
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.RS 4n
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Display information about the configuration. If specified with no other
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options, instead display information about the cache file
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(\fB/etc/zfs/zpool.cache\fR). To specify the cache file to display, see
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\fB-U\fR.
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.P
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If specified multiple times, and a pool name is also specified display both
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the cached configuration and the on-disk configuration. If specified multiple
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times with \fB-e\fR also display the configuration that would be used were the
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pool to be imported.
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.RE
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.sp
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.ne 2
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.na
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\fB-d\fR
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.ad
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.sp .6
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.RS 4n
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Display information about datasets. Specified once, displays basic dataset
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information: ID, create transaction, size, and object count.
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.sp
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If specified multiple times provides greater and greater verbosity.
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.sp
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If object IDs are specified, display information about those specific objects only.
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.RE
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.sp
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.ne 2
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.na
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\fB-D\fR
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.ad
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.sp .6
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.RS 4n
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Display deduplication statistics, including the deduplication ratio (dedup),
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compression ratio (compress), inflation due to the zfs copies property
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(copies), and an overall effective ratio (dedup * compress / copies).
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.sp
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If specified twice, display a histogram of deduplication statistics, showing
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the allocated (physically present on disk) and referenced (logically
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referenced in the pool) block counts and sizes by reference count.
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.sp
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If specified a third time, display the statistics independently for each deduplication table.
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.sp
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If specified a fourth time, dump the contents of the deduplication tables describing duplicate blocks.
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.sp
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If specified a fifth time, also dump the contents of the deduplication tables describing unique blocks.
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.RE
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.sp
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.ne 2
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.na
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\fB-h\fR
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.ad
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.sp .6
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.RS 4n
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Display pool history similar to \fBzpool history\fR, but include internal
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changes, transaction, and dataset information.
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.RE
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.sp
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.ne 2
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.na
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\fB-i\fR
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.ad
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.sp .6
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.RS 4n
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Display information about intent log (ZIL) entries relating to each
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dataset. If specified multiple times, display counts of each intent log
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transaction type.
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.RE
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.sp
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.ne 2
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.na
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\fB-l\fR \fIdevice\fR
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.ad
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.sp .6
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.RS 4n
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Display the vdev labels from the specified device. If the \fB-u\fR option is
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also specified, also display the uberblocks on this device.
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.RE
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.sp
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.ne 2
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.na
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\fB-L\fR
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.ad
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.sp .6
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.RS 4n
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Disable leak tracing and the loading of space maps. By default, \fBzdb\fR
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verifies that all non-free blocks are referenced, which can be very expensive.
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.RE
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.sp
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.ne 2
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.na
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\fB-m\fR
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.ad
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.sp .6
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.RS 4n
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Display the offset, spacemap, and free space of each metaslab.
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When specified twice, also display information about the on-disk free
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space histogram associated with each metaslab. When specified three time,
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display the maximum contiguous free space, the in-core free space histogram,
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and the percentage of free space in each space map. When specified
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four times display every spacemap record.
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.RE
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.sp
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.ne 2
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.na
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\fB-M\fR
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.ad
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.sp .6
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.RS 4n
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Display the offset, spacemap, and free space of each metaslab.
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When specified twice, also display information about the maximum contiguous
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free space and the percentage of free space in each space map. When specified
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three times display every spacemap record.
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.RE
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.sp
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.ne 2
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.na
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\fB-R\fR \fIpoolname\fR \fIvdev\fR:\fIoffset\fR:\fIsize\fR[:\fIflags\fR]
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.ad
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.sp .6
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.RS 4n
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Read and display a block from the specified device. By default the block is
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displayed as a hex dump, but see the description of the \'r\' flag, below.
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.sp
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The block is specified in terms of a colon-separated tuple \fIvdev\fR (an
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integer vdev identifier) \fIoffset\fR (the offset within the vdev) \fIsize\fR
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(the size of the block to read) and, optionally, \fIflags\fR (a set of flags,
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described below).
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.sp
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.ne 2
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.na
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\fBb\fR \fIoffset\fR
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.ad
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.sp .6
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.RS 4n
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Print block pointer
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.RE
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.sp
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.ne 2
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.na
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\fBd\fR
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.ad
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.sp .6
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.RS 4n
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Decompress the block
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.RE
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.sp
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.ne 2
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.na
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\fBe\fR
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.ad
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.sp .6
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.RS 4n
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Byte swap the block
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.RE
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.sp
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.ne 2
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.na
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\fBg\fR
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.ad
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.sp .6
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.RS 4n
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Dump gang block header
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.RE
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.sp
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.ne 2
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.na
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\fBi\fR
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.ad
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.sp .6
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.RS 4n
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Dump indirect block
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.RE
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.sp
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.ne 2
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.na
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\fBr\fR
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.ad
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.sp .6
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.RS 4n
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Dump raw uninterpreted block data
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.RE
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.RE
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.sp
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.ne 2
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.na
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\fB-s\fR
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.ad
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.sp .6
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.RS 4n
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Report statistics on \fBzdb\fR\'s I/O. Display operation counts, bandwidth,
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and error counts of I/O to the pool from \fBzdb\fR.
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.RE
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.sp
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.ne 2
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.na
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\fB-S\fR
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.ad
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.sp .6
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.RS 4n
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Simulate the effects of deduplication, constructing a DDT and then display
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that DDT as with \fB-DD\fR.
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.RE
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.sp
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.ne 2
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.na
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\fB-u\fR
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.ad
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.sp .6
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.RS 4n
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Display the current uberblock.
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.RE
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.P
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Other options:
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.sp
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.ne 2
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.na
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\fB-A\fR
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.ad
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.sp .6
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.RS 4n
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Do not abort should any assertion fail.
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.RE
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.sp
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.ne 2
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.na
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\fB-AA\fR
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.ad
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.sp .6
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.RS 4n
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Enable panic recovery, certain errors which would otherwise be fatal are
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demoted to warnings.
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.RE
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.sp
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.ne 2
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.na
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\fB-AAA\fR
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.ad
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.sp .6
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.RS 4n
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Do not abort if asserts fail and also enable panic recovery.
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.RE
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.sp
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.ne 2
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.na
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\fB-e\fR [-p \fIpath\fR]...
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.ad
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.sp .6
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.RS 4n
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Operate on an exported pool, not present in \fB/etc/zfs/zpool.cache\fR. The
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\fB-p\fR flag specifies the path under which devices are to be searched.
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.RE
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.sp
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.ne 2
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.na
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\fB-x\fR \fIdumpdir\fR
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.ad
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.sp .6
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.RS 4n
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All blocks accessed will be copied to files in the specified directory.
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The blocks will be placed in sparse files whose name is the same as
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that of the file or device read. zdb can be then run on the generated files.
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Note that the \fB-bbc\fR flags are sufficient to access (and thus copy)
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all metadata on the pool.
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.RE
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.sp
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.ne 2
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.na
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\fB-F\fR
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.ad
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.sp .6
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.RS 4n
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Attempt to make an unreadable pool readable by trying progressively older
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transactions.
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.RE
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.sp
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.ne 2
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.na
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\fB-I \fIinflight I/Os\fR \fR
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.ad
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.sp .6
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.RS 4n
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Limit the number of outstanding checksum I/Os to the specified value. The
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default value is 200. This option affects the performance of the \fB-c\fR
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option.
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.RE
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.sp
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.ne 2
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.na
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\fB-P\fR
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.ad
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.sp .6
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.RS 4n
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Print numbers in an unscaled form more amenable to parsing, eg. 1000000 rather
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than 1M.
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.RE
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.sp
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.ne 2
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.na
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\fB-t\fR \fItransaction\fR
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.ad
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.sp .6
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.RS 4n
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Specify the highest transaction to use when searching for uberblocks. See also
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the \fB-u\fR and \fB-l\fR options for a means to see the available uberblocks
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and their associated transaction numbers.
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.RE
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.sp
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.ne 2
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.na
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\fB-U\fR \fIcachefile\fR
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.ad
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.sp .6
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.RS 4n
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Use a cache file other than \fB/etc/zfs/zpool.cache\fR.
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.RE
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.sp
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.ne 2
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.na
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\fB-v\fR
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.ad
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.sp .6
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.RS 4n
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Enable verbosity. Specify multiple times for increased verbosity.
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.RE
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.sp
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.ne 2
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.na
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\fB-X\fR
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.ad
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.sp .6
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.RS 4n
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Attempt \'extreme\' transaction rewind, that is attempt the same recovery as
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\fB-F\fR but read transactions otherwise deemed too old.
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.RE
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.sp
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.ne 2
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.na
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\fB-V\fR
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.ad
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.sp .6
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.RS 4n
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Attempt a verbatim import. This mimics the behavior of the kernel when loading
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a pool from a cachefile.
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.RE
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.P
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Specifying a display option more than once enables verbosity for only that
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option, with more occurrences enabling more verbosity.
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.P
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If no options are specified, all information about the named pool will be
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displayed at default verbosity.
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.SH "EXAMPLES"
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.LP
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\fBExample 1 \fRDisplay the configuration of imported pool 'rpool'
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.sp
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.in +2
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.nf
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# zdb -C rpool
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MOS Configuration:
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version: 28
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name: 'rpool'
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...
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.fi
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.in -2
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.sp
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.LP
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\fBExample 2 \fRDisplay basic dataset information about 'rpool'
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.sp
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.in +2
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.nf
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# zdb -d rpool
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Dataset mos [META], ID 0, cr_txg 4, 26.9M, 1051 objects
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Dataset rpool/swap [ZVOL], ID 59, cr_txg 356, 486M, 2 objects
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...
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.fi
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.in -2
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.sp
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.LP
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\fBExample 3 \fRDisplay basic information about object 0
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in 'rpool/export/home'
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.sp
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|
.in +2
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.nf
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# zdb -d rpool/export/home 0
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Dataset rpool/export/home [ZPL], ID 137, cr_txg 1546, 32K, 8 objects
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Object lvl iblk dblk dsize lsize %full type
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0 7 16K 16K 15.0K 16K 25.00 DMU dnode
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.fi
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.in -2
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.sp
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.LP
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|
\fBExample 4 \fRDisplay the predicted effect of enabling deduplication on 'rpool'
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.sp
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.in +2
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|
.nf
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|
# zdb -S rpool
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|
Simulated DDT histogram:
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|
bucket allocated referenced
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______ ______________________________ ______________________________
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refcnt blocks LSIZE PSIZE DSIZE blocks LSIZE PSIZE DSIZE
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------ ------ ----- ----- ----- ------ ----- ----- -----
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1 694K 27.1G 15.0G 15.0G 694K 27.1G 15.0G 15.0G
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2 35.0K 1.33G 699M 699M 74.7K 2.79G 1.45G 1.45G
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...
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dedup = 1.11, compress = 1.80, copies = 1.00, dedup * compress / copies = 2.00
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.fi
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.in -2
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|
.sp
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.SH "ENVIRONMENT VARIABLES"
|
|
.TP
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.B "SPA_CONFIG_PATH"
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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.
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.SH "SEE ALSO"
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zfs(8), zpool(8)
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