HDFS-8633. Fix setting of dfs.datanode.readahead.bytes in hdfs-default.xml to match DFSConfigKeys. Contributed by Ray Chiang.

(cherry picked from commit b42f1ec13d0a837f188cf424a8dd177720478cc9)

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -137,6 +137,9 @@ Release 2.7.1 - UNRELEASED
 
     HDFS-4660. Block corruption can happen during pipeline recovery (kihwal)
 
+    HDFS-8633. Fix setting of dfs.datanode.readahead.bytes in hdfs-default.xml
+    to match DFSConfigKeys. (Ray Chiang via Yongjun Zhang)
+
 Release 2.7.0 - 2015-04-20
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml

@@ -1044,7 +1044,7 @@
 
 <property>
   <name>dfs.datanode.readahead.bytes</name>
-  <value>4193404</value>
+  <value>4194304</value>
   <description>
         While reading block files, if the Hadoop native libraries are available,
         the datanode can use the posix_fadvise system call to explicitly