<samba:parameter name="level2 oplocks"
context="S"
xmlns:samba="http://samba.org/common">
<listitem>
<para>This parameter controls whether Samba supports
level2 (read-only) oplocks on a share.</para>
<para>Level2, or read-only oplocks allow Windows NT clients
that have an oplock on a file to downgrade from a read-write oplock
to a read-only oplock once a second client opens the file (instead
of releasing all oplocks on a second open, as in traditional,
exclusive oplocks). This allows all openers of the file that
support level2 oplocks to cache the file for read-ahead only (ie.
they may not cache writes or lock requests) and increases performance
for many accesses of files that are not commonly written (such as
application .EXE files).</para>
<para>Once one of the clients which have a read-only oplock
writes to the file all clients are notified (no reply is needed
or waited for) and told to break their oplocks to "none" and
delete any read-ahead caches.</para>
<para>It is recommended that this parameter be turned on to
speed access to shared executables.</para>
<para>For more discussions on level2 oplocks see the CIFS spec.</para>
<para>Currently, if <link linkend="KERNELOPLOCKS"><parameter moreinfo="none">kernel
oplocks</parameter></link> are supported then level2 oplocks are
not granted (even if this parameter is set to <constant>yes</constant>).
Note also, the <link linkend="OPLOCKS"><parameter moreinfo="none">oplocks</parameter>
</link> parameter must be set to <constant>yes</constant> on this share in order for
this parameter to have any effect.</para>
<para>See also the <link linkend="OPLOCKS"><parameter moreinfo="none">oplocks</parameter>
</link> and <link linkend="OPLOCKS"><parameter moreinfo="none">kernel oplocks</parameter>
</link> parameters.</para>
<para>Default: <command moreinfo="none">level2 oplocks = yes</command></para>
</listitem>
</samba:parameter>