xnbd-wrapper(8) [debian man page]
XNBD-WRAPPER(8) System Manager's Manual XNBD-WRAPPER(8) NAME
xnbd-wrapper -- manage multiple files to be exported as a block device to other computers running the GNU/Linux(tm) Operating System SYNOPSIS
xnbd-wrapper [ --imgfile IMAGE [--imgfile IMAGE ...] ] [--laddr ADDRESS] [--port PORT] [--socket PATH] [--xnbd-binary PATH] [--daemonize] [--logpath PATH] DESCRIPTION
xnbd-wrapper is a super-server for xnbd-server. Its purpose is to manage multiple exported images at once. A client may connect to this super-server and it will be indirected to the actual xnbd-server providing the requested resource. xnbd-wrapper comes handy if you want to export multiple files (or block devices) on a single host. Instead of starting multiple xnbd-server instances and remember the exported port for each, you can use xnbd-wrapper to looks up the requested image file name and map it automati- cally to the corresponding xnbd-server. OPTIONS
The following options are supported: --daemonize Go into background as soon as the xnbd-server is started up --imgfile IMAGE Export the image file IMAGE through xnbd-wrapper, with IMAGE being a block device or a file name of an image file. xnbd-wrapper will export the file name accessible through this name to clients, which may connect to the server by providing this name This option can be specified multiple times. In this case, xnbd-wrapper will export all IMAGE files at once. Alternatively this argument can be omitted and images may be (un-)exported ar runtime with xnbd-wrapper-ctl. --laddr ADDRESS The address, where this wrapper shall listen for incoming connections. You can specify any resolvable hostname or IP address, being in IPv4 or IPv6 notation. --logpath FILE Log informational messages to the given FILE if given. Defaults to /var/log/xnbd-wrapper.log --lport PORT Accept incoming connections on the given PORT. A valid port is any number between 1 and 65536. You may not use the same listeing port more than once per system. If this argument is not given, xNBD will listen on port 8520 by default. --socket PATH The xNBD wrapper can be controlled through a control socket. When given, use PATH as file name, default is /tmp/xnbd_wrap- per.ctl). --xnbd-binary PATH Specifies the path to the xnbd-server program. The wrapper will spawn server instances on demand. Give PATH as file name, default is xnbd-server (relative to the directory, where the wrapper is in). SEE ALSO
xnbd-client (1), xnbd-server (8), xnbd-wrapper-ctl (8). AUTHOR
The NBD kernel module and the NBD tools have been written by Pavel Macheck (pavel@ucw.cz) and is now maintained by Paul Clements. (Paul.Clements@steeleye.com). The xNBD userland (client and server) have been written by Takahiro Hirofuchi (t.hirofuchi@aist.go.jp) This manual page was written by Arno Toell (debian@toell.net) 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. XNBD-WRAPPER(8)
Check Out this Related Man Page
XNBD-CLIENT(1) General Commands Manual XNBD-CLIENT(1) NAME
xnbd-client -- connect to a server running xnbd-server(8), to use its exported block device SYNOPSIS
xnbd-client [--blocksize SIZE] [--connect] [--exportname NAME] [--recovery-command COMMAND] [--recovery-command-reboot COMMAND] [--retry COUNT] [--timeout SECONDS] NBD-DEVICE [ HOST PORT ...] xnbd-client [bs=SIZE] [timeout=SECONDS] HOST PORT NBD-DEVICE xnbd-client --disconnect NBD-DEVICE xnbd-client --check NBD-DEVICE DESCRIPTION
With xnbd-client, you can connect to a server running xnbd-server or xnbd-wrapper, thus using raw diskspace from that server as a blockde- vice on the local client. To do this, support from the Linux Kernel is necessary, in the form of the Network Block Device (NBD). When you have that, either in the kernel, or as a module, you can connect to an NBD server and use its exported file through a block special file with major mode 43. Long options can also be specified with two leading dashes. Some options are call compatible to nbd-client(1) as are most behavioural switches. This makes xnbd-client a plug-in replacement for nbd-client. OPTIONS
The following options are supported: --blocksize SIZE Use the provided value as block size. Default is 1024; allowed values are either 512, 1024, 2048 or 4096. For best results use a block size value of 4096 For compatibility to nbd-client(1) you can also use bs=SIZE --check|-c Check whether the specified nbd device is connected. If the device is connected, xnbd-client will exit with an exit state of 0 and print the PID of the xnbd-client instance that con- nected it to stdout. If the device is not connected or does not exist (for example because the nbd module was not loaded), xnbd-client will exit with an exit state of 1 and not print anything on stdout. If an error occurred, xnbd-client will exit with an exit state of 2, and not print anything on stdout either. --connect|-C Connect to the nbd-server --disconnect|-d Disconnect the specified nbd device from the server. Terminates execution with an exit state of 0 on success. --exportname NAME If the server supports to access devices by an identifier, use NAME to request access to a particular volume. This command is useful in combination with a xnbd-wrapper and only succeeds, if the remote host is exporting the requested device. --retry COUNT Try up to "COUNT" times to connect to the associated nbd-server. Default is 1, that is nbd-client will stop after the first unsuccessful try. --recovery-command invoke a specified command "COMMAND" on unexpected disconnection --recovery-command-reboot Invoke the reboot(8) command on unexpected disconnection --timeout SECONDS Use a timeout period (default is 0 which means not to use a timeout). Please do not use this option for now, as it seems not to work due to a bug in the kernel module. For compatibility to nbd-client(1) you can also use timeout=SECONDS POSITIONAL ARGUMENTS
The following positional options are supported: HOST The site to connect to a remote xnbd-server. You can specify any resolvable hostname, IPv4 or IPv6 address. PORT The port number to connect to on remote side NBD-DEVICE The local nbd-device to be associated with the remote xnbd-server. You can specify multiple host port tuples. xnbd-client will try to connect to each of them in order until it succeeds to establish a connection to a server. BUGS
The NBD device is known to deadlock when not being used altogether with the deadline scheduler. Make sure to do: echo deadline > /sys/block/nbd0/queue/scheduler SEE ALSO
xnbd-server (8), xnbd-wrapper (8). AUTHOR
The NBD kernel module and the NBD tools have been written by Pavel Macheck (pavel@ucw.cz) and is now maintained by Paul Clements. (Paul.Clements@steeleye.com). The xNBD userland (client and server) have been written by Takahiro Hirofuchi (t.hirofuchi@aist.go.jp) This manual page was written by Arno Toell (debian@toell.net) for the Debian GNU/Linux system (but may be used by others). Large parts are verbatim copies of the original nbd-server and nbd-client manual pages written by Wouter Verhelst (wouter@debian.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. XNBD-CLIENT(1)