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.\" ========================================================================
.\"
.IX Title "nbdinfo 1"
.TH nbdinfo 1 "2021-02-09" "libnbd-1.6.1" "LIBNBD"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
nbdinfo \- display information and metadata about NBD servers and exports
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& nbdinfo [\-\-json] [\-\-map] [\-\-size] NBD\-URI
\&
\& nbdinfo \-L|\-\-list NBD\-URI
\&
\& nbdinfo \-\-help
\&
\& nbdinfo \-\-version
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
nbdinfo displays information and metadata about an \s-1NBD\s0 server.  The
only required parameter is the \s-1NBD URI\s0 of the server (see
https://github.com/NetworkBlockDevice/nbd/blob/master/doc/uri.md):
.PP
.Vb 10
\& $ nbdinfo nbd://localhost
\& protocol: newstyle\-fixed without TLS
\& export="":
\&         export\-size: 1048576
\&         content: data
\&         is_rotational: false
\&         is_read_only: false
\&         can_cache: true
\&         can_df: true
\&         can_fast_zero: true
\&         can_flush: true
\&         can_fua: true
\&         can_multi_conn: true
\&         can_trim: true
\&         can_zero: true
\&         block_size_minimum: 1
\&         block_size_preferred: 4096
\&         block_size_maximum: 33554432
.Ve
.PP
For an \s-1NBD\s0 server on a local Unix domain socket you would use a
command such as this (with the same output as above):
.PP
.Vb 1
\& $ nbdinfo "nbd+unix:///?socket=/tmp/unixsock"
.Ve
.SS "Size"
.IX Subsection "Size"
To display only the size in bytes of the \s-1NBD\s0 export (useful for
scripting) use the \fI\-\-size\fR parameter:
.PP
.Vb 2
\& $ nbdinfo \-\-size nbd://localhost
\& 1048576
.Ve
.SS "\s-1JSON\s0 output"
.IX Subsection "JSON output"
To display the output as \s-1JSON\s0 (eg. for scripting with \fBjq\fR\|(1)) add
the \fI\-\-json\fR parameter:
.PP
.Vb 10
\& $ nbdinfo \-\-json nbd://localhost | jq
\& {
\&   "protocol": "newstyle\-fixed",
\&   "TLS": false,
\&   "exports": [
\&     {
\&       "export\-name": "",
\&       "content": "DOS/MBR boot sector; partition 1 : ID=0xc, start\-CHS (0x3ff,254,63), end\-CHS (0x3ff,254,63), startsector 2048, 4148704 sectors",
\&       "is_rotational": false,
\&       "is_read_only": true,
\&       "can_cache": true,
\&       "can_df": true,
\&       "can_fast_zero": false,
\&       "can_flush": false,
\&       "can_fua": false,
\&       "can_multi_conn": true,
\&       "can_trim": false,
\&       "can_zero": false,
\&       "block_size_minimum": 1,
\&       "block_size_preferred": 4096,
\&       "block_size_maximum": 33554432,
\&       "export\-size": 2125119488
\&     }
\&   ]
\& }
.Ve
.SS "Map"
.IX Subsection "Map"
To show a map of which areas of the disk are allocated and sparse, use
the \fI\-\-map\fR option:
.PP
.Vb 3
\& $ nbdinfo \-\-map nbd://localhost/
\&       0  1048576  0  allocated
\& 1048576  1048576  3  hole,zero
.Ve
.PP
The fields are: start, size, type, description (optional).
.PP
The type field is an integer showing the raw value from the \s-1NBD\s0
protocol.  For some maps nbdinfo knows how to translate the type into
a printable description.
.PP
To get parseable \s-1JSON\s0 output, add \fI\-\-json\fR:
.PP
.Vb 5
\& $ nbdinfo \-\-map \-\-json nbd://localhost/
\& [{ "offset": 0, "length": 1048576,
\&    "type": 0, "description": "allocated" },
\&  { "offset": 1048576, "length": 1048576,
\&    "type": 3, "description": "hole,zero" }]
.Ve
.PP
By default this shows the \f(CW"base:allocation"\fR map, but you can show
other maps too:
.PP
.Vb 2
\& $ nbdinfo \-\-map=qemu:dirty\-bitmap:bitmap nbd://localhost/
\& 0  1048576  1  dirty
.Ve
.PP
For more information on \s-1NBD\s0 maps, see \fIMetadata querying\fR in the \s-1NBD\s0
protocol.
.SS "List all exports"
.IX Subsection "List all exports"
To list all the exports available on an \s-1NBD\s0 server use the \fI\-\-list\fR
(\fI\-L\fR) option.
.SS "Alternative tools"
.IX Subsection "Alternative tools"
You could use \f(CW\*(C`qemu\-img info\*(C'\fR (see \fBqemu\-img\fR\|(1)) to query a
single export from an \s-1NBD\s0 server.  \f(CW\*(C`qemu\-nbd \-L\*(C'\fR (see
\&\fBqemu\-nbd\fR\|(8)) can list \s-1NBD\s0 exports.  \fBnbdsh\fR\|(1) or the \fBlibnbd\fR\|(3)
\&\s-1API\s0 can be used for more complex queries.
.SH "OPTIONS"
.IX Header "OPTIONS"
.IP "\fB\-\-help\fR" 4
.IX Item "--help"
Display brief command line help and exit.
.IP "\fB\-\-content\fR" 4
.IX Item "--content"
.PD 0
.IP "\fB\-\-no\-content\fR" 4
.IX Item "--no-content"
.PD
Mostly the information displayed comes from the metadata sent by the
\&\s-1NBD\s0 server during the handshake.  However nbdinfo also downloads a
small amount of data from the beginning of the export to try to probe
the content with \fBfile\fR\|(1).
.Sp
When \fInot\fR using \fI\-\-list\fR, the default is \fI\-\-content\fR, ie.  probing
the content.  To prevent content probing, use \fI\-\-no\-content\fR.
.Sp
When using \fI\-\-list\fR, the default is \fI\-\-no\-content\fR (since
downloading from each export is expensive).  To enable content probing
use \fI\-\-list \-\-content\fR.
.IP "\fB\-\-json\fR" 4
.IX Item "--json"
The output is displayed in \s-1JSON\s0 format.
.IP "\fB\-\-map\fR" 4
.IX Item "--map"
.PD 0
.IP "\fB\-\-map=\fR\s-1MAP\s0" 4
.IX Item "--map=MAP"
.PD
Display the map (usually whether parts of the disk are allocated or
sparse) of the given export.  This displays the \f(CW"base:allocation"\fR
map by default, you can choose a different map with the optional
parameter.
.IP "\fB\-L\fR" 4
.IX Item "-L"
.PD 0
.IP "\fB\-\-list\fR" 4
.IX Item "--list"
.PD
List all the exports on an \s-1NBD\s0 server.  The export name in the \s-1NBD URI\s0
is ignored.
.IP "\fB\-\-size\fR" 4
.IX Item "--size"
Display only the size in bytes of the export.
.IP "\fB\-V\fR" 4
.IX Item "-V"
.PD 0
.IP "\fB\-\-version\fR" 4
.IX Item "--version"
.PD
Display the package name and version and exit.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBlibnbd\fR\|(3),
\&\fBnbdcopy\fR\|(1),
\&\fBnbdfuse\fR\|(1),
\&\fBnbdsh\fR\|(1),
\&\fBfile\fR\|(1),
\&\fBjq\fR\|(1),
\&\fBqemu\-img\fR\|(1),
\&\fBqemu\-nbd\fR\|(8).
.SH "AUTHORS"
.IX Header "AUTHORS"
Richard W.M. Jones
.PP
Eric Blake
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright (C) 2020 Red Hat Inc.
.SH "LICENSE"
.IX Header "LICENSE"
This library is free software; you can redistribute it and/or
modify it under the terms of the \s-1GNU\s0 Lesser General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
.PP
This library is distributed in the hope that it will be useful,
but \s-1WITHOUT ANY WARRANTY\s0; without even the implied warranty of
\&\s-1MERCHANTABILITY\s0 or \s-1FITNESS FOR A PARTICULAR PURPOSE.\s0  See the \s-1GNU\s0
Lesser General Public License for more details.
.PP
You should have received a copy of the \s-1GNU\s0 Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, \s-1MA 02110\-1301 USA\s0