Import illumos changeset 13618:c6ae14a341e8 [1]:

2088 zdb could use a reasonable manual page

Rewrite new zdb manpage to mdoc(7)

References:
https://www.illumos.org/issues/2088

PR:		kern/167467 [1]
Submitted by:	Marcelo Araujo <araujo@FreeBSD.org> [1]
Reviewed by:	mm
Obtained from:	Illumos (issue #2088)
MFC after:	1 week
This commit is contained in:
Martin Matuska 2012-05-10 04:11:39 +00:00
parent 2fccbf04cc
commit 9846ab4ed2
Notes: svn2git 2020-12-20 02:59:44 +00:00
svn path=/head/; revision=235212
2 changed files with 280 additions and 50 deletions

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@ -1,61 +1,286 @@
'\" te
.\" Copyright (c) 2011, Martin Matuska <mm@FreeBSD.org>.
.\" Copyright (c) 2012, Martin Matuska <mm@FreeBSD.org>.
.\" All Rights Reserved.
.\"
.\" The contents of this file are subject to the terms of the
.\" Common Development and Distribution License (the "License").
.\" You may not use this file except in compliance with the License.
.\" This file and its contents are supplied under the terms of the
.\" Common Development and Distribution License ("CDDL"), version 1.0.
.\" You may only use this file in accordance with the terms of version
.\" 1.0 of the CDDL.
.\"
.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
.\" or http://www.opensolaris.org/os/licensing.
.\" See the License for the specific language governing permissions
.\" and limitations under the License.
.\" A full copy of the text of the CDDL should have accompanied this
.\" source. A copy of the CDDL is also available via the Internet at
.\" http://www.illumos.org/license/CDDL.
.\"
.\" When distributing Covered Code, include this CDDL HEADER in each
.\" file and include the License file at usr/src/OPENSOLARIS.LICENSE.
.\" If applicable, add the following below this CDDL HEADER, with the
.\" fields enclosed by brackets "[]" replaced with your own identifying
.\" information: Portions Copyright [yyyy] [name of copyright owner]
.\"
.\" Copyright (c) 2004, Sun Microsystems, Inc. All Rights Reserved.
.\" Copyright 2012, Richard Lowe.
.\" Copyright (c) 2012, Marcelo Araujo <araujo@FreeBSD.org>.
.\" All Rights Reserved.
.\"
.\" $FreeBSD$
.\"
.Dd November 26, 2011
.Dd May 10, 2012
.Dt ZDB 8
.Os
.Sh NAME
.Nm zdb
.Nd ZFS debugger
.Nd Display zpool debugging and consistency information
.Sh SYNOPSIS
.Nm
.Ar pool
.Op Fl CumdibcsDvhLXFPA
.Op Fl e Op Fl p Ar path...
.Op Fl t Ar txg
.Ar poolname
.Op Ar object ...
.Nm
.Op Fl divPA
.Op Fl e Op Fl p Ar path...
.Ar dataset
.Op Ar object ...
.Nm
.Fl m Op Fl LXFPA
.Op Fl t Ar txg
.Op Fl e Op Fl p Ar path...
.Ar poolname
.Nm
.Fl R Op Fl A
.Op Fl e Op Fl p Ar path...
.Ar poolname
.Ar vdev Ns : Ns Ar offset Ns : Ns Ar size Ns Op Ns : Ns Ar flags
.Nm
.Fl S
.Op Fl AP
.Op Fl e Op Fl p Ar path...
.Ar poolname
.Nm
.Fl l
.Op Fl uA
.Ar device
.Nm
.Fl C
.Op Fl A
.Op Fl U Ar cache
.Sh DESCRIPTION
The
.Nm
command is used by support engineers to diagnose failures and
gather statistics. Since the
.Tn ZFS
file system is always consistent on disk and is self-repairing,
.Nm
should only be run under the direction by a support engineer.
utility displays information about a ZFS pool useful for debugging and
performs some amount of consistency checking.
It is a not a general purpose tool and options (and facilities) may change.
This is neither a
.Xr fsck 8
nor a
.Xr fsdb 8
utility.
.Pp
If no arguments are specified,
.Nm
performs basic consistency checks on the pool and associated datasets, and
report any problems detected.
.Nm
Any options supported by this command are internal to Sun and subject to change
at any time.
.Sh EXIT STATUS
The following exit values are returned:
.Bl -tag -offset 2n -width 2n
.It 0
The pool is consistent.
.It 1
An error was detected.
.It 2
Invalid command line options were specified.
The output of this command in general reflects the on-disk structure of a ZFS
pool, and is inherently unstable.
The precise output of most invocations is not documented, a knowledge of ZFS
internals is assumed.
.Pp
When operating on an imported and active pool it is possible, though unlikely,
that zdb may interpret inconsistent pool data and behave erratically.
.Sh OPTIONS
Display options:
.Bl -tag -width indent
.It Fl b
Display statistics regarding the number, size (logical, physical and
allocated) and deduplication of blocks.
.It Fl c
Verify the checksum of all metadata blocks while printing block statistics
(see
.Fl b Ns ).
.Pp
If specified multiple times, verify the checksums of all blocks.
.It Fl C
Display information about the configuration. If specified with no other
options, instead display information about the cache file
.Ns ( Pa /etc/zfs/zpool.cache Ns ).
To specify the cache file to display, see
.Fl U
.Pp
If specified multiple times, and a pool name is also specified display both
the cached configuration and the on-disk configuration.
If specified multiple times with
.FL e
also display the configuration that would be used were the pool to be
imported.
.It Fl d
Display information about datasets. Specified once, displays basic dataset
information: ID, create transaction, size, and object count.
.Pp
If specified multiple times provides greater and greater verbosity.
.Pp
If object IDs are specified, display information about those specific objects only.
.It Fl D
Display deduplication statistics, including the deduplication ratio (dedup),
compression ratio (compress), inflation due to the zfs copies property
(copies), and an overall effective ratio (dedup * compress / copies).
.Pp
If specified twice, display a histogram of deduplication statistics, showing
the allocated (physically present on disk) and referenced (logically
referenced in the pool) block counts and sizes by reference count.
.It Fl h
Display pool history similar to
.Cm zpool history ,
but include internal changes, transaction, and dataset information.
.It Fl i
Display information about intent log (ZIL) entries relating to each
dataset.
If specified multiple times, display counts of each intent log transaction
type.
.It Fl l Ar device
Display the vdev labels from the specified device.
If the
.Fl u
option is also specified, also display the uberblocks on this device.
.It Fl L
Disable leak tracing and the loading of space maps.
By default,
.Nm
verifies that all non-free blocks are referenced, which can be very expensive.
.It Fl m
Display the offset, spacemap, and free space of each metaslab.
When specified twice, also display information about the maximum contiguous
free space and the percentage of free space in each space map.
When specified three times display every spacemap record.
.It Xo
.Fl R Ar poolname
.Ar vdev Ns : Ns Ar offset Ns : Ns Ar size Ns Op Ns : Ns Ar flags
.Xc
Read and display a block from the specified device. By default the block is
displayed as a hex dump, but see the description of the
.Fl r
flag, below.
.Pp
The block is specified in terms of a colon-separated tuple
.Ar vdev
(an integer vdev identifier)
.Ar offset
(the offset within the vdev)
.Ar size
(the size of the block to read) and, optionally,
.Ar flags
(a set of flags, described below).
.Bl -tag -width indent
.It Sy b offset
Print block pointer
.It Sy d
Decompress the block
.It Sy e
Byte swap the block
.It Sy g
Dump gang block header
.It Sy i
Dump indirect block
.It Sy r
Dump raw uninterpreted block data
.El
.It Fl s
Report statistics on
.Nm Ns 's
I/O.
Display operation counts, bandwidth, and error counts of I/O to the pool from
.Nm .
.It Fl S
Simulate the effects of deduplication, constructing a DDT and then display
that DDT as with \fB-DD\fR.
.It Fl u
Display the current uberblock.
.El
.Pp
Other options:
.Bl -tag -width indent
.It Fl A
Do not abort should any assertion fail.
.It Fl AA
Enable panic recovery, certain errors which would otherwise be fatal are
demoted to warnings.
.It Fl AAA
Do not abort if asserts fail and also enable panic recovery.
.It Fl e Op Fl p Ar path...
Operate on an exported pool, not present in
.Pa /etc/zfs/zpool.cache .
The
.Fl p
flag specifies the path under which devices are to be searched.
.It Fl F
Attempt to make an unreadable pool readable by trying progressively older
transactions.
.It Fl P
Print numbers in an unscaled form more amenable to parsing, eg. 1000000 rather
than 1M.
.It Fl t Ar transaction
Specify the highest transaction to use when searching for uberblocks.
See also the
.Fl u
and
.Fl l
options for a means to see the available uberblocks and their associated
transaction numbers.
.It Fl U Ar cachefile
Use a cache file other than
.Pa /etc/zfs/zpool.cache .
This option is only valid with
.Fl C
.It Fl v
Enable verbosity.
Specify multiple times for increased verbosity.
.It Fl X
Attempt
.Ql extreme
transaction rewind, that is attempt the same recovery as
.Fl F
but read transactions otherwise deemed too old.
.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
.Bl -tag -width 0n
.It Sy Example 1 Display the configuration of imported pool 'rpool'
.Bd -literal -offset 2n
.Li # Ic zdb -C rpool
MOS Configuration:
version: 28
name: 'rpool'
...
.Ed
.It Sy Example 2 Display basic dataset information about 'rpool'
.Bd -literal -offset 2n
.Li # Ic zdb -d 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
.It Xo Sy Example 3 Display basic information about object 0 in
.Sy 'rpool/export/home'
.Xc
.Bd -literal -offset 2n
.Li # Ic zdb -d 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
.It Xo Sy Example 4 Display the predicted effect of enabling deduplication on
.Sy 'rpool'
.Xc
.Bd -literal -offset 2n
.Li # Ic zdb -S 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
.El
.Sh SEE ALSO
.Xr zfs 8 ,
@ -64,16 +289,18 @@ Invalid command line options were specified.
This manual page is a
.Xr mdoc 7
reimplementation of the
.Tn OpenSolaris
.Tn illumos
manual page
.Em zdb(1M) ,
modified and customized for
.Fx
and licensed under the
.Tn Common Development and Distribution License
Common Development and Distribution License
.Pq Tn CDDL .
.Pp
The
.Xr mdoc 7
implementation of this manual page was initially written by
.An Martin Matuska Aq mm@FreeBSD.org .
.An Martin Matuska Aq mm@FreeBSD.org
and
.An Marcelo Araujo Aq araujo@FreeBSD.org .

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@ -102,13 +102,16 @@ static void
usage(void)
{
(void) fprintf(stderr,
"Usage: %s [-CumdibcsDvhL] poolname [object...]\n"
" %s [-div] dataset [object...]\n"
" %s -m [-L] poolname [vdev [metaslab...]]\n"
" %s -R poolname vdev:offset:size[:flags]\n"
" %s -S poolname\n"
" %s -l [-u] device\n"
" %s -C\n\n",
"Usage: %s [-CumdibcsDvhLXFPA] [-t txg] [-e [-p path...]]"
"poolname [object...]\n"
" %s [-divPA] [-e -p path...] dataset [object...]\n"
" %s -m [-LXFPA] [-t txg] [-e [-p path...]]"
"poolname [vdev [metaslab...]]\n"
" %s -R [-A] [-e [-p path...]] poolname "
"vdev:offset:size[:flags]\n"
" %s -S [-PA] [-e [-p path...]] poolname\n"
" %s -l [-uA] device\n"
" %s -C [-A] [-U config]\n\n",
cmdname, cmdname, cmdname, cmdname, cmdname, cmdname, cmdname);
(void) fprintf(stderr, " Dataset name must include at least one "
@ -150,7 +153,7 @@ usage(void)
"has altroot/not in a cachefile\n");
(void) fprintf(stderr, " -p <path> -- use one or more with "
"-e to specify path to vdev dir\n");
(void) fprintf(stderr, " -P print numbers parsable\n");
(void) fprintf(stderr, " -P print numbers in parseable form\n");
(void) fprintf(stderr, " -t <txg> -- highest txg to use when "
"searching for uberblocks\n");
(void) fprintf(stderr, "Specify an option more than once (e.g. -bb) "