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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>
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