1@example 2@c man begin SYNOPSIS 3@command{qemu-nbd} [OPTION]... @var{filename} 4 5@command{qemu-nbd} @option{-d} @var{dev} 6@c man end 7@end example 8 9@c man begin DESCRIPTION 10 11Export a QEMU disk image using the NBD protocol. 12 13@c man end 14 15@c man begin OPTIONS 16@var{filename} is a disk image filename, or a set of block 17driver options if @var{--image-opts} is specified. 18 19@var{dev} is an NBD device. 20 21@table @option 22@item --object type,id=@var{id},...props... 23Define a new instance of the @var{type} object class identified by @var{id}. 24See the @code{qemu(1)} manual page for full details of the properties 25supported. The common object types that it makes sense to define are the 26@code{secret} object, which is used to supply passwords and/or encryption 27keys, and the @code{tls-creds} object, which is used to supply TLS 28credentials for the qemu-nbd server. 29@item -p, --port=@var{port} 30The TCP port to listen on (default @samp{10809}) 31@item -o, --offset=@var{offset} 32The offset into the image 33@item -b, --bind=@var{iface} 34The interface to bind to (default @samp{0.0.0.0}) 35@item -k, --socket=@var{path} 36Use a unix socket with path @var{path} 37@item --image-opts 38Treat @var{filename} as a set of image options, instead of a plain 39filename. If this flag is specified, the @var{-f} flag should 40not be used, instead the '@code{format=}' option should be set. 41@item -f, --format=@var{fmt} 42Force the use of the block driver for format @var{fmt} instead of 43auto-detecting 44@item -r, --read-only 45Export the disk as read-only 46@item -P, --partition=@var{num} 47Only expose partition @var{num} 48@item -s, --snapshot 49Use @var{filename} as an external snapshot, create a temporary 50file with backing_file=@var{filename}, redirect the write to 51the temporary one 52@item -l, --load-snapshot=@var{snapshot_param} 53Load an internal snapshot inside @var{filename} and export it 54as an read-only device, @var{snapshot_param} format is 55'snapshot.id=[ID],snapshot.name=[NAME]' or '[ID_OR_NAME]' 56@item -n, --nocache 57@itemx --cache=@var{cache} 58The cache mode to be used with the file. See the documentation of 59the emulator's @code{-drive cache=...} option for allowed values. 60@item --aio=@var{aio} 61Set the asynchronous I/O mode between @samp{threads} (the default) 62and @samp{native} (Linux only). 63@item --discard=@var{discard} 64Control whether @dfn{discard} (also known as @dfn{trim} or @dfn{unmap}) 65requests are ignored or passed to the filesystem. @var{discard} is one of 66@samp{ignore} (or @samp{off}), @samp{unmap} (or @samp{on}). The default is 67@samp{ignore}. 68@item --detect-zeroes=@var{detect-zeroes} 69Control the automatic conversion of plain zero writes by the OS to 70driver-specific optimized zero write commands. @var{detect-zeroes} is one of 71@samp{off}, @samp{on} or @samp{unmap}. @samp{unmap} 72converts a zero write to an unmap operation and can only be used if 73@var{discard} is set to @samp{unmap}. The default is @samp{off}. 74@item -c, --connect=@var{dev} 75Connect @var{filename} to NBD device @var{dev} 76@item -d, --disconnect 77Disconnect the device @var{dev} 78@item -e, --shared=@var{num} 79Allow up to @var{num} clients to share the device (default @samp{1}) 80@item -t, --persistent 81Don't exit on the last connection 82@item -x, --export-name=@var{name} 83Set the NBD volume export name. This switches the server to use 84the new style NBD protocol negotiation 85@item -D, --description=@var{description} 86Set the NBD volume export description, as a human-readable 87string. Requires the use of @option{-x} 88@item --tls-creds=ID 89Enable mandatory TLS encryption for the server by setting the ID 90of the TLS credentials object previously created with the --object 91option. 92@item --fork 93Fork off the server process and exit the parent once the server is running. 94@item -v, --verbose 95Display extra debugging information 96@item -h, --help 97Display this help and exit 98@item -V, --version 99Display version information and exit 100@item -T, --trace [[enable=]@var{pattern}][,events=@var{file}][,file=@var{file}] 101@findex --trace 102@include qemu-option-trace.texi 103@end table 104 105@c man end 106 107@ignore 108 109@setfilename qemu-nbd 110@settitle QEMU Disk Network Block Device Server 111 112@c man begin AUTHOR 113Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>. 114This is free software; see the source for copying conditions. There is NO 115warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 116@c man end 117 118@c man begin SEEALSO 119qemu(1), qemu-img(1) 120@c man end 121 122@end ignore 123