<para><command>&dhpackage;</command> allows to configure the
nbd-server.</para>
- <para>The default configuration file is
- <filename>@sysconfdir@/nbd-server/config</filename>, but this
- can be varied with the <option>-C</option> option to
- <command>nbd-server</command>(1).
+ <para>While
+ <filename>@sysconfdir@/nbd-server/config</filename> is the default
+ configuration file, this can be varied with the <option>-C</option>
+ option to <command>nbd-server</command>(1).
</para>
<para>
The configuration file consists of section header lines, comment
followed by an equals sign ("="), followed by the option
value. An option can be of type string, of type integer, or of
type boolean. The value of a boolean option can be denoted with
- either true or false (so not yes, no, on, off, 1, or 0); all
- booleans default to false unless specified otherwise; no value
- may be quoted (always enter it directly); for a string option,
+ either true or false (so not yes, no, on, off, 1, or 0). All
+ booleans default to false unless specified otherwise. No value
+ may be quoted (always enter it directly). For a string option,
leading whitespace is stripped (but trailing whitespace is not).
</para>
</para>
</listitem>
</varlistentry>
+ <varlistentry>
+ <term><option>oldstyle</option></term>
+ <listitem>
+ <para>
+ Optional; boolean
+ </para>
+ <para>
+ If this option is set to true, nbd-server will export all
+ exports on a separate port with the old (pre-2.9.17)
+ handshake protocol. In that case, the 'port' option for
+ individual exports is mandatory.
+ </para>
+ <para>
+ If the option is set to false, the 'port' option for
+ individual exports is optional (and will be ignored if
+ specified). The server will only export devices on the
+ standard port.
+ </para>
+ <para>
+ For upgrades from pre-2.9.17 versions of nbd, it may be
+ appropriate to enable the oldstyle parameter until all
+ clients have been converted to using name-based exports.
+ </para>
+ <para>
+ Note that exports specified on the command line will
+ always use the old handshake protocol and will not allow
+ name-based exports.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>listenaddr</option></term>
+ <listitem>
+ <para>
+ Optional; string
+ </para>
+ <para>If this option is set, it should contain the local IP
+ address on which we should listen to
+ <command>nbd-client</command>(8) connections. If it is not
+ set, <command>nbd-server</command> will listen to all
+ local IPv4 and IPv6 addresses. To limit to IPv6, specify the
+ address as "::". To limit to IPv4, specify as "0.0.0.0". It
+ is not possible to specify more than one IP address
+ here.</para>
+ </listitem>
+ </varlistentry
</variablelist>
+ </refsect1>
<refsect1>
<title>OPTIONS FOR EXPORT SECTIONS</title>
</listitem>
</varlistentry>
<varlistentry>
- <term><option>autoreadonly</option></term>
- <listitem>
- <para>Optional; boolean.</para>
- <para>
- If this option is set to true, then
- <command>nbd-server</command> will automatically switch to
- readonly if it cannot write to the file.
- </para>
- <para>Does not have a corresponding command-line
- argument</para>
- <para>TODO: verify whether this option actually works as
- documented. I have a feeling I've been terribly
- stupid.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
<term><option>copyonwrite</option></term>
<listitem>
<para>
<listitem>
<para>Required; string.</para>
<para>
- The name of the file that will be exported. This must be a
- fully-qualified path and filename; relative paths are not
- allowed.
+ The name of the file (or block device) that will be
+ exported. This must be a fully-qualified path and filename;
+ relative paths are not allowed.
</para>
<para>
Note that <command>nbd-server</command> will only try to
</listitem>
</varlistentry>
<varlistentry>
+ <term>listenaddr</term>
+ <listitem>
+ <para>
+ Optional; string
+ </para>
+ <para>
+ If the 'oldstyle' global parameter is specified, works
+ similarly to the global listenaddr parameter, but for the
+ individual port of this particular export. If the 'oldstyle'
+ parameter is not set, this parameter is ignored.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
<term><option>multifile</option></term>
<listitem>
<para>Optional; boolean.</para>
form
<replaceable>exportname</replaceable>.<replaceable>integer</replaceable>,
with <replaceable>exportname</replaceable> being the
- filename that would otherwise have been used (after
- name transformation for virtualization, if any, has been
+ filename that would otherwise have been used (after name
+ transformation for virtualization, if any, has been
performed) and <replaceable>integer</replaceable> an
integer number, starting with 0 and ending when no more
files can be found.
<varlistentry>
<term><option>port</option></term>
<listitem>
- <para>Required; integer.</para>
+ <para>Required if 'oldstyle' global parameter is set; integer.</para>
<para>
The port on which this export is to be served. Currently
it is not possible to export multiple block devices on the
</listitem>
</varlistentry>
<varlistentry>
+ <term><option>sdp</option></term>
+ <listitem>
+ <para>Optional; boolean.</para>
+ <para>
+ When this option is enabled, <command>nbd-server</command>
+ will use the Socket Direct Protocol (SDP) to serve the
+ export, rather than just IP. This is faster, but requires
+ special hardware (usually something like InfiniBand) and
+ support in the kernel.
+ </para>
+ <para>
+ Additionally, support for this option must be enabled at
+ compile time, using the <option>--enable-sdp</option> option
+ to the <command>configure</command> script. If this option
+ is found in a configuration file and
+ <command>nbd-server</command> does not have support for SDP,
+ then <command>nbd-server</command> will exit with an error
+ message.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>sync</option></term>
+ <listitem>
+ <para>Optional; boolean.</para>
+ <para>When this option is enabled,
+ <command>nbd-server</command> will call an fsync() after every
+ write to the backend storage. Calling fsync() increases
+ reliability in case of an unclean shutdown of nbd-server; but,
+ depending on the file system used on the nbd-server side, may
+ degrade performance. The use of this option isn't always
+ necessary; e.g., on ext3 filesystems, it is recommended that
+ it is <emphasis>not</emphasis> enabled, since it seriously
+ reduces performance on ext3 filesystems while not
+ importantly impacting reliability.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
<term><option>sparse_cow</option></term>
<listitem>
<para>Optional; boolean.</para>
will use sparse files to implement the copy-on-write
option; such files take up less space then they appear to,
which allows <command>nbd-server</command> to handle the
- file as if it was just as large as the block device it's for.
+ file as if it was just as large as the block device it's
+ for.
</para>
<para>
If this option is disabled, <command>nbd-server</command>
<command>nbd-server</command> will look for the
literal string '%s' in the
<option>exportname</option>, and replace it by the
- IP address of the connecting host in dotted-quad
- notation. The string that results from this
- transformation will be used as an absolute pathname
- that <command>nbd-server</command> will attempt to
- open. As an example, if a client connects from
- 192.168.1.100 and <option>exportname</option> is
- specified as <filename>/export/%s</filename>, then
- nbd-server will attempt to serve
+ address of the connecting host. The string that
+ results from this transformation will be used as an
+ absolute pathname that <command>nbd-server</command>
+ will attempt to open. As an example, if a client
+ connects from 192.168.1.100 and
+ <option>exportname</option> is specified as
+ <filename>/export/%s</filename>, then nbd-server
+ will attempt to serve
<filename>/export/192.168.1.100</filename>
</para>
</listitem>
open <filename>/export/192/168/1/100</filename>
instead.
</para>
+ <para>
+ Since there are no dots in most IPv6 addresses, the
+ effect of using this option when IPv6 is in use is
+ indistinguishable from the ipliteral option.
+ </para>
</listitem>
</varlistentry>
<varlistentry>
after it. <command>nbd-server</command> will use the
number as a network mask in CIDR style, and use that
as a hash cutoff point. In the above example, if
- <option>virtstyle</option> has been specified
- as <constant>cidrhash 16</constant>, then
+ <option>virtstyle</option> has been specified as
+ <constant>cidrhash 16</constant>, then
<command>nbd-server</command> will try to open
- <filename>/export/192.168.0.0/192.168.1.100</filename>; if
- <option>virtstyle</option> were specified as
+ <filename>/export/192.168.0.0/192.168.1.100</filename>;
+ if <option>virtstyle</option> were specified as
<constant>cidrhash 26</constant>, then
<command>nbd-server</command> will try to open
<filename>/export/192.168.1.64/192.168.1.100</filename>.
</para>
+ <para>This option works as expected for IPv6.</para>
</listitem>
</varlistentry>
</variablelist>
</listitem>
</varlistentry>
+ <varlistentry>
+ <term><option>prerun</option></term>
+ <listitem>
+ <para>Optional; string</para>
+ <para>
+ If specified, then this command will be ran after a
+ client has connected to the server (and has been
+ accepted), but before the server starts serving. If
+ the command contains the literal string '%s', then
+ this string will be replaced by the filename of the
+ file which nbd-server wants to export.
+ </para>
+ <para>
+ This is useful to create export files on the fly, or
+ to verify that a file can be used for export, to
+ write something to a log file, or similar.
+ </para>
+ <para>
+ If the command runs with a non-zero exit status,
+ then nbd-server will assume the export will fail,
+ and refuse to serve it.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>postrun</option></term>
+ <listitem>
+ <para>Optional; string</para>
+ <para>
+ If specified, then it is assumed to be a command
+ that will be ran when a client has
+ disconnected. This can be useful to clean up
+ whatever <option>prerun</option> has set up, to log
+ something, or similar.
+ </para>
+ <para>
+ If the literal string '%s' is present in the
+ command, it will be replaced by the file name that
+ has just been closed.
+ </para>
+ <para>
+ In contrast to the <option>prerun</option> option,
+ the exit state of <option>postrun</option> is
+ <emphasis>ignored</emphasis>.
+ </para>
+ </listitem>
+ </varlistentry>
</variablelist>
-
+
</refsect1>
<refsect1>
<title>SEE ALSO</title>
projects / nbd.git / blobdiff