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<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE refentry PUBLIC "-//Samba-Team//DTD DocBook V4.2-Based Variant V1.0//EN" "http://www.samba.org/samba/DTD/samba-doc">
<refentry id="vfs_aio_fork.8">

<refmeta>
	<refentrytitle>vfs_aio_fork</refentrytitle>
	<manvolnum>8</manvolnum>
	<refmiscinfo class="source">Samba</refmiscinfo>
	<refmiscinfo class="manual">System Administration tools</refmiscinfo>
	<refmiscinfo class="version">&doc.version;</refmiscinfo>
</refmeta>


<refnamediv>
	<refname>vfs_aio_fork</refname>
	<refpurpose>implement async I/O in Samba vfs</refpurpose>
</refnamediv>

<refsynopsisdiv>
	<cmdsynopsis>
		<command>vfs objects = aio_fork</command>
	</cmdsynopsis>
</refsynopsisdiv>

<refsect1>
	<title>DESCRIPTION</title>

	<para>This VFS module is part of the
	<citerefentry><refentrytitle>samba</refentrytitle>
	<manvolnum>7</manvolnum></citerefentry> suite.</para>

	<para>The <command>aio_fork</command> VFS module enables async
	I/O for Samba on platforms where the system level Posix AIO
	interface is insufficient. Posix AIO can suffer from severe
	limitations.  For example, on some Linux versions the
	real-time signals that it uses are broken under heavy load.
	Other systems only allow AIO when special kernel modules are
	loaded or only allow a certain system-wide amount of async
	requests being scheduled. Systems based on glibc (most Linux
	systems) only allow a single outstanding request per file
	descriptor.  </para>

	<para>To work around all these limitations, the aio_fork module
	was written. It uses forked helper processes instead of the
	internal Posix AIO interface to create asynchronousity for
	read and write calls. It has no parameters, it will create
	helper processes when async requests come in as needed. Idle
	helper processes will be removed every 30 seconds.
	</para>

	<para>This module is stackable.</para>

</refsect1>


<refsect1>
	<title>EXAMPLES</title>

	<para>Straight forward use:</para>

<programlisting>
        <smbconfsection name="[cooldata]"/>
	<smbconfoption name="path">/data/ice</smbconfoption>
	<smbconfoption name="vfs objects">aio_fork</smbconfoption>
</programlisting>

</refsect1>

<refsect1>
	<title>VERSION</title>

	<para>This man page is part of version &doc.version; of the Samba suite.
	</para>
</refsect1>

<refsect1>
	<title>AUTHOR</title>

	<para>The original Samba software and related utilities
	were created by Andrew Tridgell. Samba is now developed
	by the Samba Team as an Open Source project similar
	to the way the Linux kernel is developed.</para>

</refsect1>

</refentry>