X-Git-Url: https://git.whamcloud.com/?a=blobdiff_plain;f=ConfiguringStorage.xml;h=b13f0dcced0e7eb8d3c63447786b575a230f4d14;hb=2c82bcd0e7356e9c228a95800789febec5fdc6b7;hp=9c2921e286fc2f70a6c87b04d2e1c101615e4c09;hpb=2865c6061d1c7e1449fc563bc719630ba5e540af;p=doc%2Fmanual.git

diff --git a/ConfiguringStorage.xml b/ConfiguringStorage.xml
index 9c2921e..b13f0dc 100644
--- a/ConfiguringStorage.xml
+++ b/ConfiguringStorage.xml
@@ -1,4 +1,7 @@
-<?xml version='1.0' encoding='UTF-8'?><chapter xmlns="http://docbook.org/ns/docbook" xmlns:xl="http://www.w3.org/1999/xlink" version="5.0" xml:lang="en-US" xml:id="configuringstorage">
+<?xml version='1.0' encoding='UTF-8'?>
+<chapter xmlns="http://docbook.org/ns/docbook"
+ xmlns:xl="http://www.w3.org/1999/xlink" version="5.0" xml:lang="en-US"
+ xml:id="configuringstorage">
   <title xml:id="configuringstorage.title">Configuring Storage on a Lustre File System</title>
   <para>This chapter describes best practices for storage selection and file system options to optimize performance on RAID, and includes the following sections:</para>
   <itemizedlist>
@@ -137,11 +140,17 @@
     </section>
     <section remap="h3">
       <title><indexterm><primary>storage</primary><secondary>configuring</secondary><tertiary>external journal</tertiary></indexterm>Choosing Parameters for an External Journal</title>
-      <para>If you have configured a RAID array and use it directly as an OST, it contains both data and metadata. For better performance, we recommend putting the OST journal on a separate device, by creating a small RAID 1 array and using it as an external journal for the OST.</para>
-      <para>In a Lustre file system, the default journal size is 400 MB. A journal size of up to 1
-        GB has shown increased performance but diminishing returns are seen for larger journals.
-        Additionally, a copy of the journal is kept in RAM. Therefore, make sure you have enough
-        memory available to hold copies of all the journals.</para>
+      <para>If you have configured a RAID array and use it directly as an OST,
+        it contains both data and metadata. For better performance, we
+        recommend putting the OST journal on a separate device, by creating a
+        small RAID 1 array and using it as an external journal for the OST.
+      </para>
+      <para>In a typical Lustre file system, the default OST journal size is
+        up to 1GB, and the default MDT journal size is up to 4GB, in order to
+        handle a high transaction rate without blocking on journal flushes.
+        Additionally, a copy of the journal is kept in RAM. Therefore, make
+        sure you have enough RAM on the servers to hold copies of all journals.
+        </para>
       <para>The file system journal options are specified to <literal>mkfs.lustre</literal> using
         the <literal>--mkfsoptions</literal> parameter. For example:</para>
       <screen>--mkfsoptions &quot;<replaceable>other_options</replaceable> -j -J device=/dev/mdJ&quot; </screen>
@@ -190,3 +199,6 @@
     </itemizedlist>
   </section>
 </chapter>
+<!--
+  vim:expandtab:shiftwidth=2:tabstop=8:
+  -->