/etc/nbdtab - configuration file for nbd-client
This file allows to configure predefined connections for nbd-client. It may
contain multiple definitions, one per line, each of which contains four
To connect a device specified in the nbdtab file, run nbd-client
the short name of that device as the sole argument. It will then look up the
required information in nbdtab
, and make the connection.
Fields are separated from one another by any number of space or tab characters;
records are separated from one another by newline characters. The file may
also contain any number of comments, which start with a '#' character and
continue until the end of the line or the end of the file, whichever is first.
The file contains the following fields:
- The short name of the device file. That is, it should
contain the name of the device without the leading /dev/ part;
e.g., it could say nbd0.
- The hostname (in case of a TCP socket) or filename (in case
of a unix domain socket) on which the server is listening.
- The name of the export as exported by
- Any extra options. This field is optional (no pun
intended), and need not appear in a file if no options are necessary. The
options recognized by nbd-client(8) are specified below, in the
section "Options". Any unknown options in this field will
produce a warning by nbd-client, unless they are prepended by an
underscore ('_') character; the underscore is specifically reserved for
local use, or for distribution customization.
Every command-line nbd-client
option which allows to configure specific
options for a particular device node has a corresponding option in the
file, and vice versa; where this isn't the case, that is a bug.
Individual options in this field should be separated from one another by the
- bs=block size
- The block size for this export. If this option is not used,
the kernel's default will be used instead.
Corresponds to the -b option on the command line.
- The number of connections to use for this device.
Corresponds to the -C option on the command line; see nbd-client(8)
for more details on that option.
- port=port number
- The port on which to communicate with the
nbd-server. Defaults to the IANA-assigned port for NBD, 10809.
- The timeout. If this option is not specified, no timeout is
Corresponds to the -t option on the command line.
- Persist the connection, using the semantics of the
-p command-line option.
- Optimize for swap; -s.
- Use the Socket Direct protocol; -S.
- Use a Unix Domain socket to connect to the server;
nbd-server (1), nbd-client (8), nbd-trdump (8)
The NBD kernel module and the NBD tools were originally written by Pavel Machek
The Linux kernel module is now maintained by Paul Clements
(Paul.Clements@steeleye.com), while the userland tools are maintained by
Wouter Verhelst (<email@example.com>)
On The Hurd there is a regular translator available to perform the client side
of the protocol, and the use of nbd-client
is not required. Please see
the relevant documentation for more information.
This manual page was written by Wouter Verhelst (<firstname.lastname@example.org>).
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.
A simple nbdtab
file could look like this:
# swap space, called "swapexport" on the server
# optimize for swap, and try to reconnect upon disconnect.
nbd0 nbdserver.example.com swapexport swap,persist
# other export, called "data" on the server. No options for this one.
nbd1 nbdserver.example.com data