mirror of
https://git.proxmox.com/git/mirror_zfs.git
synced 2024-11-17 18:11:00 +03:00
d2734cce68
Details about the motivation of this feature and its usage can
be found in this blogpost:
https://sdimitro.github.io/post/zpool-checkpoint/
A lightning talk of this feature can be found here:
https://www.youtube.com/watch?v=fPQA8K40jAM
Implementation details can be found in big block comment of
spa_checkpoint.c
Side-changes that are relevant to this commit but not explained
elsewhere:
* renames members of "struct metaslab trees to be shorter without
losing meaning
* space_map_{alloc,truncate}() accept a block size as a
parameter. The reason is that in the current state all space
maps that we allocate through the DMU use a global tunable
(space_map_blksz) which defauls to 4KB. This is ok for metaslab
space maps in terms of bandwirdth since they are scattered all
over the disk. But for other space maps this default is probably
not what we want. Examples are device removal's vdev_obsolete_sm
or vdev_chedkpoint_sm from this review. Both of these have a
1:1 relationship with each vdev and could benefit from a bigger
block size.
Porting notes:
* The part of dsl_scan_sync() which handles async destroys has
been moved into the new dsl_process_async_destroys() function.
* Remove "VERIFY(!(flags & FWRITE))" in "kernel.c" so zhack can write
to block device backed pools.
* ZTS:
* Fix get_txg() in zpool_sync_001_pos due to "checkpoint_txg".
* Don't use large dd block sizes on /dev/urandom under Linux in
checkpoint_capacity.
* Adopt Delphix-OS's setting of 4 (spa_asize_inflation =
SPA_DVAS_PER_BP + 1) for the checkpoint_capacity test to speed
its attempts to fill the pool
* Create the base and nested pools with sync=disabled to speed up
the "setup" phase.
* Clear labels in test pool between checkpoint tests to avoid
duplicate pool issues.
* The import_rewind_device_replaced test has been marked as "known
to fail" for the reasons listed in its DISCLAIMER.
* New module parameters:
zfs_spa_discard_memory_limit,
zfs_remove_max_bytes_pause (not documented - debugging only)
vdev_max_ms_count (formerly metaslabs_per_vdev)
vdev_min_ms_count
Authored by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: John Kennedy <john.kennedy@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Richard Lowe <richlowe@richlowe.net>
Ported-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Tim Chase <tim@chase2k.com>
OpenZFS-issue: https://illumos.org/issues/9166
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/7159fdb8
Closes #7570
419 lines
11 KiB
Groff
419 lines
11 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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.\"
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.\" Copyright 2012, Richard Lowe.
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.\" Copyright (c) 2012, 2017 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 April 14, 2017
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.Dt ZDB 8 SMM
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.Os Linux
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.Sh NAME
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.Nm zdb
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.Nd display zpool debugging and consistency information
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.Sh SYNOPSIS
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.Nm
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.Op Fl AbcdDFGhikLMPsvX
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.Op Fl e Oo Fl V Oc Op Fl p Ar path ...
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.Op Fl I Ar inflight I/Os
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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 Ar poolname Op Ar object ...
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.Nm
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.Op Fl AdiPv
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.Op Fl e Oo Fl V Oc Op Fl p Ar path ...
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.Op Fl U Ar cache
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.Ar dataset Op Ar object ...
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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 \&: 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 AFLPX
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.Op Fl e Oo Fl V Oc Op Fl p Ar path ...
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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 Op Ar metaslab ...
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.Nm
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.Fl O
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.Ar dataset path
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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 Op Fl p Ar path ...
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.Op Fl U Ar cache
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.Ar poolname vdev Ns \&: Ns Ar offset Ns \&: Ns Ar size 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 Op Fl p Ar path ...
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.Op Fl U Ar cache
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.Ar poolname
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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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This is neither a
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.Xr fsck 1M
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nor an
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.Xr fsdb 1M
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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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.Ar pool Ns /
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.Pq pool name followed by a slash .
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.Pp
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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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.Bl -tag -width Ds
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.It Fl b
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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 c
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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
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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
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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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.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 are specified, display information about those specific objects
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only.
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.It Fl D
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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 * 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 Ar word0 Ns \&: 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
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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
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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
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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 Ar device
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Read the vdev labels 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. 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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.It Fl lll Ar device
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Display every configuration, unique or not.
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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.
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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. Specify
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multiple times to increase verbosity.
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.It Fl L
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Disable leak tracing 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
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Display the offset, spacemap, and free space of each metaslab.
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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
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Display the offset, spacemap, and free space of each metaslab.
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.It Fl MM
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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 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 Xo
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.Fl R Ar poolname vdev Ns \&: Ns Ar offset Ns \&: Ns Ar size 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 size of the block to read
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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
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.It Sy d
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Decompress the block. Set environment variable
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.Nm ZBD_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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.El
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.It Fl s
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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
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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
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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
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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 Op Fl p Ar path ...
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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 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
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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
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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 Ar inflight I/Os
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Limit the number of outstanding checksum I/Os 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 o Ar var Ns = Ns Ar value ...
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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
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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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.It Fl t 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 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
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Enable verbosity.
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Specify multiple times for increased verbosity.
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.It Fl V
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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
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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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.El
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.Pp
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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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.Pp
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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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.Bl -tag -width Ds
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.It Xo
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.Sy Example 1
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Display the configuration of imported pool
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.Pa rpool
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.Xc
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.Bd -literal
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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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.Ed
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.It Xo
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.Sy Example 2
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Display basic dataset information about
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.Pa rpool
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.Xc
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.Bd -literal
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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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.Ed
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.It Xo
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.Sy Example 3
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Display basic information about object 0 in
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.Pa rpool/export/home
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.Xc
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.Bd -literal
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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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.Ed
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.It Xo
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.Sy Example 4
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Display the predicted effect of enabling deduplication on
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.Pa rpool
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.Xc
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.Bd -literal
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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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.Ed
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.El
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.Sh SEE ALSO
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.Xr zfs 8 ,
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.Xr zpool 8
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