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xnbd-register - Restore xNBD sessions upon boot



xnbd-register - Restore xNBD sessions upon boot


xnbd-register [OPTIONS] --start
xnbd-register [OPTIONS] --stop
xnbd-register [OPTIONS] --restart
xnbd-register [OPTIONS] --status


With the xnbd-register command one can restore xnbd-wrapper and xnbd-client sessions based on a configuration file. This is useful to start client, wrapper or both upon boot.
To achieve this, xnbd-register reads a semi-structured configuration file located in /etc/xnbd.conf. See below for format hints.


The following options are supported:
Start devices configured in the configuration files. If the configuration files describes volumes, xnbd-register will try to establish a client connection to the configured wrapper instance.
Alternatively, xnbd-register will start sharing configured volumes by starting an xnbd-wrapper super server.
Retrieve wrapper status from a running xnbd-wrapper command, if applicable.
Analogous to the start option, the stop argument will stop all xnbd connection, being client or wrapper instances.
Restart all xnbd instances, being client or wrapper
--config FILE
Config file to use. Defaults to /etc/xnbd.conf.
Do not produce verbose output


xnbd-register will read its defaults from /etc/xnbd.conf. This is a semi-structured configuration file, describing client and wrapper connections that are supposed to be restored upon start of the system.
The syntax of the file is a JSON data structure, allowing comments starting with a hash key ("#"). Two types of objects are recognized: xnbd volumes and a wrapper instance. xnbd volumes are indexed by the supposed devices name. This is, to restore /dev/nbd0 an object named "nbd0" must be configured. Valid arguments are host, name and port. So, for example, this is to configure /dev/nbd0 connecting to localhost on port 8520. If present, identify the shared device by the configured logical name:
"nbd0": {
    "host": "",
    "port": 8520,
    "name": "name"
Similarly, a wrapper instance configures an xnbd-wrapper. Valid options are:
Specifies the listening address
Specifies the listening port
Specifies the listening socket for the control channels
Specifies the log path where logging output is being redirected to
A mapping of volumes which are exported. Mapping keys are export names, mapping values are disk image paths.
"wrapper": {
    "address": "",
    "port": 8520,
    "socket": "/var/run/xnbd.ctl",
    "logpath": "/var/log/xnbd.log",
    "volumes": {
        "one": "/dev/volume",
        "two": "/dev/sdb1",
        "three": "/var/lib/image.file",


xnbd-wrapper(8), xnbd-client(1)


xnbd-register was written by Arno Toell ( for the Debian GNU/Linux system.
This manual page was written by Arno Toell ( for the Debian GNU/Linux system (but may be used by others). Permission is granted to copy, distribute and/or modify this document under the terms of the GNU General Public License, version 2, as published by the Free Software Foundation.
02/12/2014 xNBD 0.3.0