HDFS.7849. Update documentation for enabling a new feature in rolling…

… upgrade ( Contributed by J.Andreina )
apache · Mar 19, 2015 · 5be5129 · 5be5129
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diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -764,6 +764,9 @@ Release 2.7.0 - UNRELEASED
 
  HDFS-7054. Make DFSOutputStream tracing more fine-grained (cmccabe)
 
+ HDFS.7849. Update documentation for enabling a new feature in rolling
+ upgrade ( J.Andreina via vinayakumarb )
+
  OPTIMIZATIONS
 
  HDFS-7454. Reduce memory footprint for AclEntries in NameNode.

diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/site/xdoc/HdfsRollingUpgrade.xml b/hadoop-hdfs-project/hadoop-hdfs/src/site/xdoc/HdfsRollingUpgrade.xml
@@ -47,6 +47,15 @@
  These two capabilities make it feasible to upgrade HDFS without incurring HDFS downtime.
  In order to upgrade a HDFS cluster without downtime, the cluster must be setup with HA.
  </p>
+ <p>
+ If there is any new feature which is enabled in new software release, may not work with old software release after upgrade.
+ In such cases upgrade should be done by following steps.
+ </p>
+ <ol>
+ <li>Disable new feature.</li>
+ <li>Upgrade the cluster.</li>
+ <li>Enable the new feature.</li>
+ </ol>
  <p>
  Note that rolling upgrade is supported only from Hadoop-2.4.0 onwards.
  </p>