samba-mirror/docs-xml/manpages/vfs_cacheprime.8.xml

<?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_cacheprime.8">

<refmeta>
	<refentrytitle>vfs_cacheprime</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_cacheprime</refname>
	<refpurpose>prime the kernel file data cache</refpurpose>
</refnamediv>

<refsynopsisdiv>
	<cmdsynopsis>
		<command>vfs objects = cacheprime</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>vfs_cacheprime</command> VFS module reads chunks
	of file data near the range requested by clients in order to
	make sure the data is present in the kernel file data cache at
	the time when it is actually requested by clients. </para>

	<para>The size of the disk read operations performed
	by <command>vfs_cacheprime</command> is determined by the
	cacheprime:rsize option. All disk read operations are aligned
	on boundaries that are a multiple of this size. Each range of
	the file data is primed at most once during the time the client
	has the file open. </para>

	<para>This module is stackable.</para>
</refsect1>

<refsect1>
	<title>OPTIONS</title>

	<variablelist>

		<varlistentry>
		<term>cacheprime:rsize = BYTES</term>
		<listitem>
		<para>The number of bytes with which to prime
		the kernel data cache.</para>
		<para>The following suffixes may be applied to BYTES:</para>
		<itemizedlist>
		<listitem><para><command>K</command> - BYTES is a number of kilobytes</para></listitem>
		<listitem><para><command>M</command> - BYTES is a number of megabytes</para></listitem>
		<listitem><para><command>G</command> - BYTES is a number of gigabytes</para></listitem>
		</itemizedlist>

		</listitem>
		</varlistentry>

	</variablelist>
</refsect1>

<refsect1>
	<title>EXAMPLES</title>

	<para>For a hypothetical disk array, it is necessary to ensure
	that all read operations are of size 1 megabyte (1048576 bytes),
	and aligned on 1 megabyte boundaries:
	</para>
<programlisting>
	<smbconfsection name="[hypothetical]"/>
	<smbconfoption name="vfs objects">cacheprime</smbconfoption>
	<smbconfoption name="cacheprime:rsize">1M</smbconfoption>
</programlisting>

</refsect1>

<refsect1>
	<title>CAVEATS</title>
	<para><command>cacheprime</command> is not a substitute for
	a general-purpose readahead mechanism. It is intended for use
	only in very specific environments where disk operations must
	be aligned and sized to known values (as much as that is possible).
	</para>
</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>