qemu-nbd(8) QEMU Disk Network Block Device Server


qemu-nbd [OPTION]... filename

qemu-nbd -d dev


Export a QEMU disk image using the NBD protocol.


filename is a disk image filename, or a set of block driver options if --image-opts is specified.

dev is an NBD device.

--object type,id=id,...props...
Define a new instance of the type object class identified by id. See the qemu(1) manual page for full details of the properties supported. The common object types that it makes sense to define are the "secret" object, which is used to supply passwords and/or encryption keys, and the "tls-creds" object, which is used to supply TLS credentials for the qemu-nbd server.
-p, --port=port
The TCP port to listen on (default 10809)
-o, --offset=offset
The offset into the image
-b, --bind=iface
The interface to bind to (default
-k, --socket=path
Use a unix socket with path path
Treat filename as a set of image options, instead of a plain filename. If this flag is specified, the -f flag should not be used, instead the '"format="' option should be set.
-f, --format=fmt
Force the use of the block driver for format fmt instead of auto-detecting
-r, --read-only
Export the disk as read-only
-P, --partition=num
Only expose partition num
-s, --snapshot
Use filename as an external snapshot, create a temporary file with backing_file=filename, redirect the write to the temporary one
-l, --load-snapshot=snapshot_param
Load an internal snapshot inside filename and export it as an read-only device, snapshot_param format is 'snapshot.id=[ID],snapshot.name=[NAME]' or '[ID_OR_NAME]'
-n, --nocache
The cache mode to be used with the file. See the documentation of the emulator's "-drive cache=..." option for allowed values.
Set the asynchronous I/O mode between threads (the default) and native (Linux only).
Control whether discard (also known as trim or unmap) requests are ignored or passed to the filesystem. discard is one of ignore (or off), unmap (or on). The default is ignore.
Control the automatic conversion of plain zero writes by the OS to driver-specific optimized zero write commands. detect-zeroes is one of off, on or unmap. unmap converts a zero write to an unmap operation and can only be used if discard is set to unmap. The default is off.
-c, --connect=dev
Connect filename to NBD device dev
-d, --disconnect
Disconnect the device dev
-e, --shared=num
Allow up to num clients to share the device (default 1)
-t, --persistent
Don't exit on the last connection
-x NAME, --export-name=NAME
Set the NBD volume export name. This switches the server to use the new style NBD protocol negotiation
Enable mandatory TLS encryption for the server by setting the ID of the TLS credentials object previously created with the --object option.
-v, --verbose
Display extra debugging information
-h, --help
Display this help and exit
-V, --version
Display version information and exit


Copyright (C) 2006 Anthony Liguori <[email protected]>. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.