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