Adding JRA's documentation on large directory (files) support.

(This used to be commit a2d2778d7da7f7fdf0a7f57a05a7ee1ffeb214af)

2 files changed, 75 insertions, 0 deletions

diff --git a/docs/Samba-HOWTO-Collection/LargeFile.xml b/docs/Samba-HOWTO-Collection/LargeFile.xml
new file mode 100644
index 0000000000..d3314df2b2
--- /dev/null
+++ b/docs/Samba-HOWTO-Collection/LargeFile.xml
@@ -0,0 +1,74 @@
+<?xml version="1.0" encoding="iso-8859-1"?>
+<!DOCTYPE book PUBLIC "-//samba//DTD Samba XML V1.0//EN" "http://www.samba.org/samba/DTD/samba-doc" [
+<!ENTITY % globalentities SYSTEM '../entities/global.entities'> %globalentities;
+]>
+
+<chapter id="AccessControls">
+<chapterinfo>
+	&author.jeremy;
+	&author.jht;
+	<pubdate>March 5, 2005</pubdate>
+</chapterinfo>
+<title>Handling Large Directories</title>
+
+<para>
+Samba-3.0.12 implements a solution for sites that have experienced performance degradation do to the
+problem of using Samba-3 with applications that need large numbers of files (100,000 or more) per directory.
+</para>
+
+<para>
+The key was fixing the directory handling to read only the current list requested instead of the old
+(up to samba-3.0.11) behaviour of reading the entire directory into memory before doling out names.
+Normally this would have broken OS/2 applications which have very strange delete semantics, but by
+stealing logic from Samba4 (thanks tridge) the current code in 3.0.12 handles this correctly.
+</para>
+
+<para>
+To set up an application that needs large number of files per directory in a way that does not
+damage performance unduly follow these steps:
+</para>
+
+<para>
+Firstly, you need to canonicalize all the files in the directory to have one case, upper or lower - take your
+pick (I chose upper as all my files were already upper case names). Then set up a new custom share for the
+application as follows:
+<screen>
+[bigshare]
+        path = /home/jeremy/tmp/manyfilesdir
+        read only = no
+        case sensitive = True
+        default case = upper
+        preserve case = no
+        short preserve case = no
+</screen>
+</para>
+
+<para>
+Of course, use your own path and settings, but set the case options to match the case of all the files in your
+directory. The path should point at the large directory needed for the application - any new files created in
+there and in any paths under it will be forced by smbd into upper case - but smbd will no longer have to scan
+the directory for names - it knows that if a file does not exist in upper case then it doesn't exist at all.
+</para>
+
+<para>
+The secret to this is really in the <smbconfoption><name>case sensitive</name><value>True</value></smbconfoption>
+line. This tells smbd never to scan for case-insensitive versions of names. So if an application asks for a file
+called <filename>FOO</filename>, and it can not be found by a simple stat call, then smbd will return file not
+found immediately without scanning the containing directory for a version of a different case. The other
+<filename>xxx case xxx</filename> lines make this work by forcing a consistent case on all files created by smbd.
+</para>
+
+<para>
+Remember, all files and directories under the <parameter>path</parameter> directory must be in upper case
+with this &smb.conf; stanza as smbd will not be able to find lower case filenames with these settings. Also
+note this is done on a per-share basis, allowing this to be set only for a share servicing an application with
+this problematic behaviour (using large numbers of entries in a directory) - the rest of your smbd shares
+don't need to be affected.
+</para>
+
+<para>
+This makes smbd much faster when dealing with large directories.  My test case has over 100,000 files and
+smbd now deals with this very efficiently.
+</para>
+
+</chapter>
diff --git a/docs/Samba-HOWTO-Collection/index.xml b/docs/Samba-HOWTO-Collection/index.xml
index 484d147814..14f595cae1 100644
--- a/docs/Samba-HOWTO-Collection/index.xml
+++ b/docs/Samba-HOWTO-Collection/index.xml
@@ -155,6 +155,7 @@ Samba has several features that you might want or might not want to use. The cha
 <xi:include href="Unicode.xml"/>
 <xi:include href="Backup.xml"/>
 <xi:include href="HighAvailability.xml"/>
+<xi:include href="LargeFile.xml"/>
 </part>
 
 <part id="migration">