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8653f1de48
This is more-or-less like `zfs send`, but specifying the snapshot by its objset id for situations where it can't be referenced any other way. Sponsored-By: Klara, Inc. Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de> Reviewed-by: WHR <msl0000023508@gmail.com> Signed-off-by: Rob Norris <rob.norris@klarasystems.com> Closes #14642
564 lines
16 KiB
Groff
564 lines
16 KiB
Groff
.\"
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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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.\" Copyright 2012, Richard Lowe.
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.\" Copyright (c) 2012, 2019 by Delphix. All rights reserved.
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.\" Copyright 2017 Nexenta Systems, Inc.
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.\" Copyright (c) 2017 Lawrence Livermore National Security, LLC.
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.\" Copyright (c) 2017 Intel Corporation.
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.\"
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.Dd June 4, 2023
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.Dt ZDB 8
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.Os
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.
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.Sh NAME
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.Nm zdb
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.Nd display ZFS storage pool debugging and consistency information
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.Sh SYNOPSIS
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.Nm
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.Op Fl AbcdDFGhikLMNPsvXYy
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.Op Fl e Oo Fl V Oc Oo Fl p Ar path Oc Ns …
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.Op Fl I Ar inflight-I/O-ops
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.Oo Fl o Ar var Ns = Ns Ar value Oc Ns …
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.Op Fl t Ar txg
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.Op Fl U Ar cache
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.Op Fl x Ar dumpdir
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.Op Fl K Ar key
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.Op Ar poolname Ns Op / Ns Ar dataset Ns | Ns Ar objset-ID
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.Op Ar object Ns | Ns Ar range Ns …
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.Nm
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.Op Fl AdiPv
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.Op Fl e Oo Fl V Oc Oo Fl p Ar path Oc Ns …
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.Op Fl U Ar cache
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.Op Fl K Ar key
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.Ar poolname Ns Op Ar / Ns Ar dataset Ns | Ns Ar objset-ID
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.Op Ar object Ns | Ns Ar range Ns …
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.Nm
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.Fl B
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.Op Fl e Oo Fl V Oc Oo Fl p Ar path Oc Ns …
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.Op Fl U Ar cache
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.Op Fl K Ar key
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.Ar poolname Ns Ar / Ns Ar objset-ID
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.Op Ar backup-flags
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.Nm
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.Fl C
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.Op Fl A
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.Op Fl U Ar cache
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.Nm
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.Fl E
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.Op Fl A
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.Ar word0 : Ns Ar word1 Ns :…: Ns Ar word15
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.Nm
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.Fl l
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.Op Fl Aqu
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.Ar device
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.Nm
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.Fl m
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.Op Fl AFLPXY
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.Op Fl e Oo Fl V Oc Oo Fl p Ar path Oc Ns …
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.Op Fl t Ar txg
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.Op Fl U Ar cache
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.Ar poolname Op Ar vdev Oo Ar metaslab Oc Ns …
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.Nm
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.Fl O
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.Op Fl K Ar key
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.Ar dataset path
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.Nm
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.Fl r
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.Op Fl K Ar key
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.Ar dataset path destination
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.Nm
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.Fl R
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.Op Fl A
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.Op Fl e Oo Fl V Oc Oo Fl p Ar path Oc Ns …
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.Op Fl U Ar cache
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.Ar poolname vdev : Ns Ar offset : Ns Oo Ar lsize Ns / Oc Ns Ar psize Ns Op : Ns Ar flags
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.Nm
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.Fl S
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.Op Fl AP
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.Op Fl e Oo Fl V Oc Oo Fl p Ar path Oc Ns …
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.Op Fl U Ar cache
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.Ar poolname
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.
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.Sh DESCRIPTION
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The
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.Nm
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utility displays information about a ZFS pool useful for debugging and performs
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some amount of consistency checking.
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It is a not a general purpose tool and options
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.Pq and facilities
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may change.
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It is not a
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.Xr fsck 8
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utility.
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.Pp
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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.
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The precise output of most invocations is not documented, a knowledge of ZFS
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internals is assumed.
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.Pp
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If the
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.Ar dataset
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argument does not contain any
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.Qq Sy /
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or
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.Qq Sy @
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characters, it is interpreted as a pool name.
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The root dataset can be specified as
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.Qq Ar pool Ns / .
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.Pp
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.Nm
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is an
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.Qq offline
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tool; it accesses the block devices underneath the pools directly from
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userspace and does not care if the pool is imported or datasets are mounted
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(or even if the system understands ZFS at all).
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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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.
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.Sh OPTIONS
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Display options:
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.Bl -tag -width Ds
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.It Fl b , -block-stats
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Display statistics regarding the number, size
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.Pq logical, physical and allocated
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and deduplication of blocks.
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.It Fl B , -backup
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Generate a backup stream, similar to
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.Nm zfs Cm send ,
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but for the numeric objset ID, and without opening the dataset.
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This can be useful in recovery scenarios if dataset metadata has become
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corrupted but the dataset itself is readable.
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The optional
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.Ar flags
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argument is a string of one or more of the letters
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.Sy e ,
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.Sy L ,
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.Sy c ,
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and
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.Sy w ,
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which correspond to the same flags in
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.Xr zfs-send 8 .
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.It Fl c , -checksum
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Verify the checksum of all metadata blocks while printing block statistics
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.Po see
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.Fl b
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.Pc .
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.Pp
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If specified multiple times, verify the checksums of all blocks.
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.It Fl C , -config
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Display information about the configuration.
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If specified with no other options, instead display information about the cache
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file
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.Pq Pa /etc/zfs/zpool.cache .
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To specify the cache file to display, see
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.Fl U .
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.Pp
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If specified multiple times, and a pool name is also specified display both the
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cached configuration and the on-disk configuration.
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If specified multiple times with
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.Fl e
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also display the configuration that would be used were the pool to be imported.
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.It Fl d , -datasets
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Display information about datasets.
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Specified once, displays basic dataset information: ID, create transaction,
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size, and object count.
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See
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.Fl N
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for determining if
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.Ar poolname Ns Op / Ns Ar dataset Ns | Ns Ar objset-ID
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is to use the specified
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.Ar dataset Ns | Ns Ar objset-ID
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as a string (dataset name) or a number (objset ID) when
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datasets have numeric names.
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.Pp
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If specified multiple times provides greater and greater verbosity.
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.Pp
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If object IDs or object ID ranges are specified, display information about
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those specific objects or ranges only.
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.Pp
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An object ID range is specified in terms of a colon-separated tuple of
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the form
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.Ao start Ac : Ns Ao end Ac Ns Op : Ns Ao flags Ac .
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The fields
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.Ar start
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and
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.Ar end
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are integer object identifiers that denote the upper and lower bounds
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of the range.
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An
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.Ar end
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value of -1 specifies a range with no upper bound.
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The
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.Ar flags
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field optionally specifies a set of flags, described below, that control
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which object types are dumped.
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By default, all object types are dumped.
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A minus sign
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.Pq -
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negates the effect of the flag that follows it and has no effect unless
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preceded by the
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.Ar A
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flag.
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For example, the range 0:-1:A-d will dump all object types except for
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directories.
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.Pp
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.Bl -tag -compact -width Ds
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.It Sy A
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Dump all objects (this is the default)
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.It Sy d
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Dump ZFS directory objects
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.It Sy f
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Dump ZFS plain file objects
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.It Sy m
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Dump SPA space map objects
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.It Sy z
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Dump ZAP objects
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.It Sy -
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Negate the effect of next flag
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.El
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.It Fl D , -dedup-stats
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Display deduplication statistics, including the deduplication ratio
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.Pq Sy dedup ,
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compression ratio
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.Pq Sy compress ,
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inflation due to the zfs copies property
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.Pq Sy copies ,
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and an overall effective ratio
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.Pq Sy dedup No \(mu Sy compress No / Sy copies .
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.It Fl DD
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Display a histogram of deduplication statistics, showing the allocated
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.Pq physically present on disk
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and referenced
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.Pq logically referenced in the pool
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block counts and sizes by reference count.
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.It Fl DDD
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Display the statistics independently for each deduplication table.
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.It Fl DDDD
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Dump the contents of the deduplication tables describing duplicate blocks.
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.It Fl DDDDD
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Also dump the contents of the deduplication tables describing unique blocks.
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.It Fl E , -embedded-block-pointer Ns = Ns Ar word0 : Ns Ar word1 Ns :…: Ns Ar word15
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Decode and display block from an embedded block pointer specified by the
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.Ar word
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arguments.
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.It Fl h , -history
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Display pool history similar to
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.Nm zpool Cm history ,
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but include internal changes, transaction, and dataset information.
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.It Fl i , -intent-logs
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Display information about intent log
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.Pq ZIL
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entries relating to each dataset.
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If specified multiple times, display counts of each intent log transaction type.
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.It Fl k , -checkpointed-state
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Examine the checkpointed state of the pool.
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Note, the on disk format of the pool is not reverted to the checkpointed state.
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.It Fl l , -label Ns = Ns Ar device
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Read the vdev labels and L2ARC header from the specified device.
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.Nm Fl l
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will return 0 if valid label was found, 1 if error occurred, and 2 if no valid
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labels were found.
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The presence of L2ARC header is indicated by a specific
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sequence (L2ARC_DEV_HDR_MAGIC).
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If there is an accounting error in the size or the number of L2ARC log blocks
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.Nm Fl l
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will return 1.
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Each unique configuration is displayed only once.
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.It Fl ll Ar device
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In addition display label space usage stats.
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If a valid L2ARC header was found
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also display the properties of log blocks used for restoring L2ARC contents
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(persistent L2ARC).
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.It Fl lll Ar device
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Display every configuration, unique or not.
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If a valid L2ARC header was found
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also display the properties of log entries in log blocks used for restoring
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L2ARC contents (persistent L2ARC).
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.Pp
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If the
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.Fl q
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option is also specified, don't print the labels or the L2ARC header.
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.Pp
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If the
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.Fl u
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option is also specified, also display the uberblocks on this device.
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Specify multiple times to increase verbosity.
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.It Fl L , -disable-leak-tracking
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Disable leak detection and the loading of space maps.
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By default,
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.Nm
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verifies that all non-free blocks are referenced, which can be very expensive.
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.It Fl m , -metaslabs
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Display the offset, spacemap, free space of each metaslab, all the log
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spacemaps and their obsolete entry statistics.
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.It Fl mm
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Also display information about the on-disk free space histogram associated with
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each metaslab.
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.It Fl mmm
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Display the maximum contiguous free space, the in-core free space histogram, and
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the percentage of free space in each space map.
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.It Fl mmmm
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Display every spacemap record.
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.It Fl M , -metaslab-groups
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Display all "normal" vdev metaslab group information - per-vdev metaslab count,
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fragmentation,
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and free space histogram, as well as overall pool fragmentation and histogram.
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.It Fl MM
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"Special" vdevs are added to -M's normal output.
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.It Fl O , -object-lookups Ns = Ns Ar dataset path
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Also display information about the maximum contiguous free space and the
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percentage of free space in each space map.
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.It Fl MMM
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Display every spacemap record.
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.It Fl N
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Same as
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.Fl d
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but force zdb to interpret the
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.Op Ar dataset Ns | Ns Ar objset-ID
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in
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.Op Ar poolname Ns Op / Ns Ar dataset Ns | Ns Ar objset-ID
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as a numeric objset ID.
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.It Fl O Ar dataset path
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Look up the specified
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.Ar path
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inside of the
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.Ar dataset
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and display its metadata and indirect blocks.
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Specified
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.Ar path
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must be relative to the root of
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.Ar dataset .
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This option can be combined with
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.Fl v
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for increasing verbosity.
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.It Fl r , -copy-object Ns = Ns Ar dataset path destination
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Copy the specified
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.Ar path
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inside of the
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.Ar dataset
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to the specified destination.
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Specified
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.Ar path
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must be relative to the root of
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.Ar dataset .
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This option can be combined with
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.Fl v
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for increasing verbosity.
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.It Xo
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.Fl R , -read-block Ns = Ns Ar poolname vdev : Ns Ar offset : Ns Oo Ar lsize Ns / Oc Ns Ar psize Ns Op : Ns Ar flags
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.Xc
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Read and display a block from the specified device.
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By default the block is displayed as a hex dump, but see the description of the
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.Sy r
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flag, below.
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.Pp
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The block is specified in terms of a colon-separated tuple
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.Ar vdev
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.Pq an integer vdev identifier
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.Ar offset
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.Pq the offset within the vdev
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.Ar size
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.Pq the physical size, or logical size / physical size
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of the block to read and, optionally,
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.Ar flags
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.Pq a set of flags, described below .
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.Pp
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.Bl -tag -compact -width "b offset"
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.It Sy b Ar offset
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Print block pointer at hex offset
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.It Sy c
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Calculate and display checksums
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.It Sy d
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Decompress the block.
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Set environment variable
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.Nm ZDB_NO_ZLE
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to skip zle when guessing.
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.It Sy e
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Byte swap the block
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.It Sy g
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Dump gang block header
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.It Sy i
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Dump indirect block
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.It Sy r
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Dump raw uninterpreted block data
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.It Sy v
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Verbose output for guessing compression algorithm
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.El
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.It Fl s , -io-stats
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Report statistics on
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.Nm zdb
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I/O.
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Display operation counts, bandwidth, and error counts of I/O to the pool from
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.Nm .
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.It Fl S , -simulate-dedup
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Simulate the effects of deduplication, constructing a DDT and then display
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that DDT as with
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.Fl DD .
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.It Fl u , -uberblock
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Display the current uberblock.
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.El
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.Pp
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Other options:
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.Bl -tag -width Ds
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.It Fl A , -ignore-assertions
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Do not abort should any assertion fail.
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.It Fl AA
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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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.It Fl AAA
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Do not abort if asserts fail and also enable panic recovery.
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.It Fl e , -exported Ns = Ns Oo Fl p Ar path Oc Ns …
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Operate on an exported pool, not present in
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.Pa /etc/zfs/zpool.cache .
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The
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.Fl p
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flag specifies the path under which devices are to be searched.
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.It Fl x , -dump-blocks Ns = Ns Ar dumpdir
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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.
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.Nm
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can be then run on the generated files.
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Note that the
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.Fl bbc
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flags are sufficient to access
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.Pq and thus copy
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all metadata on the pool.
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.It Fl F , -automatic-rewind
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Attempt to make an unreadable pool readable by trying progressively older
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transactions.
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.It Fl G , -dump-debug-msg
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Dump the contents of the zfs_dbgmsg buffer before exiting
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.Nm .
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zfs_dbgmsg is a buffer used by ZFS to dump advanced debug information.
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.It Fl I , -inflight Ns = Ns Ar inflight-I/O-ops
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Limit the number of outstanding checksum I/O operations to the specified value.
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The default value is 200.
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This option affects the performance of the
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.Fl c
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option.
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.It Fl K , -key Ns = Ns Ar key
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Decryption key needed to access an encrypted dataset.
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This will cause
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.Nm
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to attempt to unlock the dataset using the encryption root, key format and other
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encryption parameters on the given dataset.
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.Nm
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can still inspect pool and dataset structures on encrypted datasets without
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unlocking them, but will not be able to access file names and attributes and
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object contents. \fBWARNING:\fP The raw decryption key and any decrypted data
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will be in user memory while
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.Nm
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is running.
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Other user programs may be able to extract it by inspecting
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.Nm
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as it runs.
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Exercise extreme caution when using this option in shared or uncontrolled
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environments.
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.It Fl o , -option Ns = Ns Ar var Ns = Ns Ar value Ns …
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Set the given global libzpool variable to the provided value.
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The value must be an unsigned 32-bit integer.
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Currently only little-endian systems are supported to avoid accidentally setting
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the high 32 bits of 64-bit variables.
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.It Fl P , -parseable
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Print numbers in an unscaled form more amenable to parsing, e.g.\&
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.Sy 1000000
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rather than
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.Sy 1M .
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.It Fl t , -txg Ns = Ns Ar transaction
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Specify the highest transaction to use when searching for uberblocks.
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See also the
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.Fl u
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and
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.Fl l
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options for a means to see the available uberblocks and their associated
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transaction numbers.
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.It Fl U , -cachefile Ns = Ns Ar cachefile
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Use a cache file other than
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.Pa /etc/zfs/zpool.cache .
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.It Fl v , -verbose
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Enable verbosity.
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Specify multiple times for increased verbosity.
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.It Fl V , -verbatim
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Attempt verbatim import.
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This mimics the behavior of the kernel when loading a pool from a cachefile.
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Only usable with
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.Fl e .
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.It Fl X , -extreme-rewind
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Attempt
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.Qq extreme
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transaction rewind, that is attempt the same recovery as
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.Fl F
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but read transactions otherwise deemed too old.
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.It Fl Y , -all-reconstruction
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Attempt all possible combinations when reconstructing indirect split blocks.
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This flag disables the individual I/O deadman timer in order to allow as
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much time as required for the attempted reconstruction.
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.It Fl y , -livelist
|
|
Perform validation for livelists that are being deleted.
|
|
Scans through the livelist and metaslabs, checking for duplicate entries
|
|
and compares the two, checking for potential double frees.
|
|
If it encounters issues, warnings will be printed, but the command will not
|
|
necessarily fail.
|
|
.El
|
|
.Pp
|
|
Specifying a display option more than once enables verbosity for only that
|
|
option, with more occurrences enabling more verbosity.
|
|
.Pp
|
|
If no options are specified, all information about the named pool will be
|
|
displayed at default verbosity.
|
|
.
|
|
.Sh EXAMPLES
|
|
.Ss Example 1 : No Display the configuration of imported pool Ar rpool
|
|
.Bd -literal
|
|
.No # Nm zdb Fl C Ar rpool
|
|
MOS Configuration:
|
|
version: 28
|
|
name: 'rpool'
|
|
…
|
|
.Ed
|
|
.
|
|
.Ss Example 2 : No Display basic dataset information about Ar rpool
|
|
.Bd -literal
|
|
.No # Nm zdb Fl d Ar rpool
|
|
Dataset mos [META], ID 0, cr_txg 4, 26.9M, 1051 objects
|
|
Dataset rpool/swap [ZVOL], ID 59, cr_txg 356, 486M, 2 objects
|
|
…
|
|
.Ed
|
|
.
|
|
.Ss Example 3 : No Display basic information about object 0 in Ar rpool/export/home
|
|
.Bd -literal
|
|
.No # Nm zdb Fl d Ar rpool/export/home 0
|
|
Dataset rpool/export/home [ZPL], ID 137, cr_txg 1546, 32K, 8 objects
|
|
|
|
Object lvl iblk dblk dsize lsize %full type
|
|
0 7 16K 16K 15.0K 16K 25.00 DMU dnode
|
|
.Ed
|
|
.
|
|
.Ss Example 4 : No Display the predicted effect of enabling deduplication on Ar rpool
|
|
.Bd -literal
|
|
.No # Nm zdb Fl S Ar rpool
|
|
Simulated DDT histogram:
|
|
|
|
bucket allocated referenced
|
|
______ ______________________________ ______________________________
|
|
refcnt blocks LSIZE PSIZE DSIZE blocks LSIZE PSIZE DSIZE
|
|
------ ------ ----- ----- ----- ------ ----- ----- -----
|
|
1 694K 27.1G 15.0G 15.0G 694K 27.1G 15.0G 15.0G
|
|
2 35.0K 1.33G 699M 699M 74.7K 2.79G 1.45G 1.45G
|
|
…
|
|
dedup = 1.11, compress = 1.80, copies = 1.00, dedup * compress / copies = 2.00
|
|
.Ed
|
|
.
|
|
.Sh SEE ALSO
|
|
.Xr zfs 8 ,
|
|
.Xr zpool 8
|