manpage.1'. You may view the manual page with: `docbook-to-man manpage.sgml | nroff -man | less'. A typical entry in a Makefile or Makefile.am is: manpage.1: manpage.sgml docbook-to-man $< > $@ --> Wouter"> Verhelst"> september 19, 2001"> 1"> wouter@debian.org"> NBD-SERVER"> Debian GNU/Linux"> GNU"> ]>

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&dhfirstname; &dhsurname; 2001 &dhusername; &dhdate; &dhucpackage; &dhsection; &dhpackage; serve a file as a block device to other computers running the &gnu;/Linux(tm) or &gnu;/Hurd Operating System &dhpackage; port filename size -r -m -c -a timeout -l host list This manual page documents the &dhpackage; command. This manual page was written for the &debian; distribution because the original program does not have a manual page. &dhpackage; is the server for the Linux Network Block Device (NBD). With NBD, a client can use a file, exported over the network from a server, as a block device. It can then be used for whatever purpose a normal block device (harddisk, CD-ROM, ...) can be used for. NBD can be useful for diskless clients that need swapspace, but you can also create a filesystem on it and use it as though it were a local filesystem. &dhpackage; implements some security through a file called "nbd_server.allow" in the current directory (by default; a different file can be chosen with the '-l' option). This file must list the IP-addresses of clients that are allowed to connect. If it does not exist, all clients are able to connect. If the file is empty, no clients can connect. port The port the server should listen to. A valid port is any number between 1 and 65536; if 0 is used, nbd-server will listen on stdin (so that nbd-server can be ran from inetd) filename The filename of the file that should be exported. This can be any file, including "real" blockdevices (i.e. a file from /dev). If the filename includes the literal string "%s", then this %s will be substituded with the IP-address of the client trying to connect. size The size of the block device at the client side. This is especially usefull in conjunction with the -m option Can optionally be followed by one of K,k,M or m, in which case the size will be multiplied by 1024 (K or k) or 1048576 (M or m) -r Export the file read-only. If a client tries to write to a read-only exported file, it will receive an error, but the connection will stay up. -m Work with multiple files. This can be used to export blockdevices that are larger than the maximum allowed filesize on a given filesystem; i.e. when the filesystem does not allow files larger than 2GB (which is true for Linux 2.2 and below), you can use this option to store the data in multiple files and export a larger filesystem, if needed. To use this option, you must create a number of files with names in the format "name.X", where "name" is given as the filename argument to nbd-server, and "X" is a number starting by 0 and going up for each file. The files must all be 1GB in size. Allowing more flexibility for this option is planned for future versions. -c Copy on write. When this option is provided, write-operations are not done to the exported file, but to a separate file. This separate file is removed when the connection is closed, which means that serving this way will make nbd-server slow down (especially on large block devices with lots of writes), and that after disconnecting and reconnecting the client or the server, all changes are lost. timeout Maximum number of idle seconds. If a connection is inactive for this amount of time, it is terminated; this is to avoid stale nbd-server processes staying in memory. Use of this option is strongly recommended. host list This argument should contain a list of IP-addresses for hosts that may connect to the server. Wildcards are not allowed. If the file does not exist, it is ignored (and any host can connect); If the file does exist, but is empty, no host can connect. By default, the name 'nbd_server.allow' is used, and looked for in the current directory, unless nbd-server is compiled as a daemon, in which case it is looked for in the root-directory. Some examples of nbd-server usage: To export a file /export/nbd/exp-bl-dev on port 2000: nbd-server 2000 /export/nbd/exp-bl-dev To export a the same file read-only: nbd-server 2000 /export/nbd/exp-bl-dev -r To export the same file read-write, but make sure changes are lost after restarting the client or the server: nbd-server 2000 /export/nbd/exp-bl-dev -c nbd-client (8), http://nbd.sourceforge.net/roadmap.html The NBD kernel module and the NBD tools were originally written by Pavel Machek (pavel@ucw.cz) The kernel module is now maintained by Paul Clements (Paul.Clements@steeleye.com), while the userland tools are maintained by &dhusername; (&dhemail;) This manual page was written by &dhusername; (&dhemail;) for the &debian; 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.