diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index 2a8da43dc7..16fe394270 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -306,6 +306,9 @@ Trunk (Unreleased)
     HDFS-7803. Wrong command mentioned in HDFSHighAvailabilityWithQJM
     documentation (Arshad Mohammad via aw)
 
+    HDFS-4681. TestBlocksWithNotEnoughRacks#testCorruptBlockRereplicatedAcrossRacks 
+    fails using IBM java (Ayappan via aw)
+
 Release 2.7.0 - UNRELEASED
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/DFSTestUtil.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/DFSTestUtil.java
index 5b391c567f..7e7ff39e89 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/DFSTestUtil.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/DFSTestUtil.java
@@ -251,6 +251,12 @@ private class MyFile {
   public void createFiles(FileSystem fs, String topdir) throws IOException {
     createFiles(fs, topdir, (short)3);
   }
+
+  public static byte[] readFileAsBytes(FileSystem fs, Path fileName) throws IOException {
+    ByteArrayOutputStream os = new ByteArrayOutputStream();
+    IOUtils.copyBytes(fs.open(fileName), os, 1024, true);
+    return os.toByteArray();
+  }
   
   /** create nFiles with random names and directory hierarchies
    *  with random (but reproducible) data in them.
@@ -723,6 +729,12 @@ public static String readFile(File f) throws IOException {
     return b.toString();
   }
 
+  public static byte[] readFileAsBytes(File f) throws IOException {
+    ByteArrayOutputStream os = new ByteArrayOutputStream();
+    IOUtils.copyBytes(new FileInputStream(f), os, 1024, true);
+    return os.toByteArray();
+  }
+
   /* Write the given string to the given file */
   public static void writeFile(FileSystem fs, Path p, String s) 
       throws IOException {
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/MiniDFSCluster.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/MiniDFSCluster.java
index 5297ba2bc7..2c1d07e716 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/MiniDFSCluster.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/MiniDFSCluster.java
@@ -1869,6 +1869,16 @@ public String readBlockOnDataNode(int i, ExtendedBlock block)
     return null;
   }
 
+  public byte[] readBlockOnDataNodeAsBytes(int i, ExtendedBlock block)
+      throws IOException {
+    assert (i >= 0 && i < dataNodes.size()) : "Invalid datanode "+i;
+    File blockFile = getBlockFile(i, block);
+    if (blockFile != null && blockFile.exists()) {
+      return DFSTestUtil.readFileAsBytes(blockFile);
+    }
+    return null;
+  }
+
   /**
    * Corrupt a block on a particular datanode.
    *
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlocksWithNotEnoughRacks.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlocksWithNotEnoughRacks.java
index 1bc7cdce4f..54983a1378 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlocksWithNotEnoughRacks.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlocksWithNotEnoughRacks.java
@@ -20,6 +20,7 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertArrayEquals;
 
 import java.util.ArrayList;
 
@@ -202,7 +203,7 @@ public void testCorruptBlockRereplicatedAcrossRacks() throws Exception {
       final FileSystem fs = cluster.getFileSystem();
       
       DFSTestUtil.createFile(fs, filePath, fileLen, REPLICATION_FACTOR, 1L);
-      final String fileContent = DFSTestUtil.readFile(fs, filePath);
+      final byte[] fileContent = DFSTestUtil.readFileAsBytes(fs, filePath);
 
       ExtendedBlock b = DFSTestUtil.getFirstBlock(fs, filePath);
       DFSTestUtil.waitForReplication(cluster, b, 2, REPLICATION_FACTOR, 0);
@@ -224,9 +225,9 @@ public void testCorruptBlockRereplicatedAcrossRacks() throws Exception {
       // Ensure all replicas are valid (the corrupt replica may not
       // have been cleaned up yet).
       for (int i = 0; i < racks.length; i++) {
-        String blockContent = cluster.readBlockOnDataNode(i, b);
+        byte[] blockContent = cluster.readBlockOnDataNodeAsBytes(i, b);
         if (blockContent != null && i != dnToCorrupt) {
-          assertEquals("Corrupt replica", fileContent, blockContent);
+          assertArrayEquals("Corrupt replica", fileContent, blockContent);
         }
       }
     } finally {