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.\" ========================================================================
.\"
.IX Title "QEMU-NBD 8"
.TH QEMU-NBD 8 "2024-11-18" " " " "
.\" 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"
qemu\-nbd \- QEMU Disk Network Block Device Server
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
\&\fBqemu-nbd\fR [\s-1OPTION\s0]... \fIfilename\fR
.PP
\&\fBqemu-nbd\fR \fB\-d\fR \fIdev\fR
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
Export a \s-1QEMU\s0 disk image using the \s-1NBD\s0 protocol.
.SH "OPTIONS"
.IX Header "OPTIONS"
\&\fIfilename\fR is a disk image filename, or a set of block
driver options if \fI\-\-image\-opts\fR is specified.
.PP
\&\fIdev\fR is an \s-1NBD\s0 device.
.IP "\fB\-\-object type,id=\fR\fIid\fR\fB,...props...\fR" 4
.IX Item "--object type,id=id,...props..."
Define a new instance of the \fItype\fR object class identified by \fIid\fR.
See the \f(CWqemu(1)\fR manual page for full details of the properties
supported. The common object types that it makes sense to define are the
\&\f(CW\*(C`secret\*(C'\fR object, which is used to supply passwords and/or encryption
keys, and the \f(CW\*(C`tls\-creds\*(C'\fR object, which is used to supply \s-1TLS\s0
credentials for the qemu-nbd server.
.IP "\fB\-p, \-\-port=\fR\fIport\fR" 4
.IX Item "-p, --port=port"
The \s-1TCP\s0 port to listen on (default \fB10809\fR)
.IP "\fB\-o, \-\-offset=\fR\fIoffset\fR" 4
.IX Item "-o, --offset=offset"
The offset into the image
.IP "\fB\-b, \-\-bind=\fR\fIiface\fR" 4
.IX Item "-b, --bind=iface"
The interface to bind to (default \fB0.0.0.0\fR)
.IP "\fB\-k, \-\-socket=\fR\fIpath\fR" 4
.IX Item "-k, --socket=path"
Use a unix socket with path \fIpath\fR
.IP "\fB\-\-image\-opts\fR" 4
.IX Item "--image-opts"
Treat \fIfilename\fR as a set of image options, instead of a plain
filename. If this flag is specified, the \fI\-f\fR flag should
not be used, instead the '\f(CW\*(C`format=\*(C'\fR' option should be set.
.IP "\fB\-f, \-\-format=\fR\fIfmt\fR" 4
.IX Item "-f, --format=fmt"
Force the use of the block driver for format \fIfmt\fR instead of
auto-detecting
.IP "\fB\-r, \-\-read\-only\fR" 4
.IX Item "-r, --read-only"
Export the disk as read-only
.IP "\fB\-P, \-\-partition=\fR\fInum\fR" 4
.IX Item "-P, --partition=num"
Only expose partition \fInum\fR
.IP "\fB\-s, \-\-snapshot\fR" 4
.IX Item "-s, --snapshot"
Use \fIfilename\fR as an external snapshot, create a temporary
file with backing_file=\fIfilename\fR, redirect the write to
the temporary one
.IP "\fB\-l, \-\-load\-snapshot=\fR\fIsnapshot_param\fR" 4
.IX Item "-l, --load-snapshot=snapshot_param"
Load an internal snapshot inside \fIfilename\fR and export it
as an read-only device, \fIsnapshot_param\fR format is
\&'snapshot.id=[\s-1ID\s0],snapshot.name=[\s-1NAME\s0]' or '[\s-1ID_OR_NAME\s0]'
.IP "\fB\-n, \-\-nocache\fR" 4
.IX Item "-n, --nocache"
.PD 0
.IP "\fB\-\-cache=\fR\fIcache\fR" 4
.IX Item "--cache=cache"
.PD
The cache mode to be used with the file.  See the documentation of
the emulator's \f(CW\*(C`\-drive cache=...\*(C'\fR option for allowed values.
.IP "\fB\-\-aio=\fR\fIaio\fR" 4
.IX Item "--aio=aio"
Set the asynchronous I/O mode between \fBthreads\fR (the default)
and \fBnative\fR (Linux only).
.IP "\fB\-\-discard=\fR\fIdiscard\fR" 4
.IX Item "--discard=discard"
Control whether \fIdiscard\fR (also known as \fItrim\fR or \fIunmap\fR)
requests are ignored or passed to the filesystem.  \fIdiscard\fR is one of
\&\fBignore\fR (or \fBoff\fR), \fBunmap\fR (or \fBon\fR).  The default is
\&\fBignore\fR.
.IP "\fB\-\-detect\-zeroes=\fR\fIdetect-zeroes\fR" 4
.IX Item "--detect-zeroes=detect-zeroes"
Control the automatic conversion of plain zero writes by the \s-1OS\s0 to
driver-specific optimized zero write commands.  \fIdetect-zeroes\fR is one of
\&\fBoff\fR, \fBon\fR or \fBunmap\fR.  \fBunmap\fR
converts a zero write to an unmap operation and can only be used if
\&\fIdiscard\fR is set to \fBunmap\fR.  The default is \fBoff\fR.
.IP "\fB\-c, \-\-connect=\fR\fIdev\fR" 4
.IX Item "-c, --connect=dev"
Connect \fIfilename\fR to \s-1NBD\s0 device \fIdev\fR
.IP "\fB\-d, \-\-disconnect\fR" 4
.IX Item "-d, --disconnect"
Disconnect the device \fIdev\fR
.IP "\fB\-e, \-\-shared=\fR\fInum\fR" 4
.IX Item "-e, --shared=num"
Allow up to \fInum\fR clients to share the device (default \fB1\fR)
.IP "\fB\-t, \-\-persistent\fR" 4
.IX Item "-t, --persistent"
Don't exit on the last connection
.IP "\fB\-x \s-1NAME,\s0 \-\-export\-name=NAME\fR" 4
.IX Item "-x NAME, --export-name=NAME"
Set the \s-1NBD\s0 volume export name. This switches the server to use
the new style \s-1NBD\s0 protocol negotiation
.IP "\fB\-\-tls\-creds=ID\fR" 4
.IX Item "--tls-creds=ID"
Enable mandatory \s-1TLS\s0 encryption for the server by setting the \s-1ID\s0
of the \s-1TLS\s0 credentials object previously created with the \-\-object
option.
.IP "\fB\-v, \-\-verbose\fR" 4
.IX Item "-v, --verbose"
Display extra debugging information
.IP "\fB\-h, \-\-help\fR" 4
.IX Item "-h, --help"
Display this help and exit
.IP "\fB\-V, \-\-version\fR" 4
.IX Item "-V, --version"
Display version information and exit
.IP "\fB\-T, \-\-trace [[enable=]\fR\fIpattern\fR\fB][,events=\fR\fIfile\fR\fB][,file=\fR\fIfile\fR\fB]\fR" 4
.IX Item "-T, --trace [[enable=]pattern][,events=file][,file=file]"
Specify tracing options.
.RS 4
.IP "\fB[enable=]\fR\fIpattern\fR" 4
.IX Item "[enable=]pattern"
Immediately enable events matching \fIpattern\fR.
The file must contain one event name (as listed in the \fItrace-events-all\fR
file) per line; globbing patterns are accepted too.  This option is only
available if \s-1QEMU\s0 has been compiled with the \fIsimple\fR, \fIstderr\fR
or \fIftrace\fR tracing backend.  To specify multiple events or patterns,
specify the \fB\-trace\fR option multiple times.
.Sp
Use \f(CW\*(C`\-trace help\*(C'\fR to print a list of names of trace points.
.IP "\fBevents=\fR\fIfile\fR" 4
.IX Item "events=file"
Immediately enable events listed in \fIfile\fR.
The file must contain one event name (as listed in the \fItrace-events-all\fR
file) per line; globbing patterns are accepted too.  This option is only
available if \s-1QEMU\s0 has been compiled with the \fIsimple\fR, \fIstderr\fR or
\&\fIftrace\fR tracing backend.
.IP "\fBfile=\fR\fIfile\fR" 4
.IX Item "file=file"
Log output traces to \fIfile\fR.
This option is only available if \s-1QEMU\s0 has been compiled with
the \fIsimple\fR tracing backend.
.RE
.RS 4
.RE
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBqemu\fR\|(1), \fBqemu\-img\fR\|(1)
.SH "AUTHOR"
.IX Header "AUTHOR"
Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>.
This is free software; see the source for copying conditions.  There is \s-1NO\s0
warranty; not even for \s-1MERCHANTABILITY\s0 or \s-1FITNESS FOR A PARTICULAR PURPOSE.\s0