diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/balancer/Balancer.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/balancer/Balancer.java
index 93270107dd..a63c3b8257 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/balancer/Balancer.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/balancer/Balancer.java
@@ -94,7 +94,7 @@
  * </pre>
  * 
  * <p>DESCRIPTION
- * <p>The threshold parameter is a fraction in the range of (0%, 100%) with a 
+ * <p>The threshold parameter is a fraction in the range of (1%, 100%) with a 
  * default value of 10%. The threshold sets a target for whether the cluster 
  * is balanced. A cluster is balanced if for each datanode, the utilization 
  * of the node (ratio of used space at the node to total capacity of the node) 
@@ -1503,14 +1503,14 @@ static Parameters parse(String[] args) {
               i++;
               try {
                 threshold = Double.parseDouble(args[i]);
-                if (threshold < 0 || threshold > 100) {
-                  throw new NumberFormatException(
+                if (threshold < 1 || threshold > 100) {
+                  throw new IllegalArgumentException(
                       "Number out of range: threshold = " + threshold);
                 }
                 LOG.info( "Using a threshold of " + threshold );
-              } catch(NumberFormatException e) {
+              } catch(IllegalArgumentException e) {
                 System.err.println(
-                    "Expecting a number in the range of [0.0, 100.0]: "
+                    "Expecting a number in the range of [1.0, 100.0]: "
                     + args[i]);
                 throw e;
               }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/balancer/TestBalancer.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/balancer/TestBalancer.java
index 81b03a568e..11dbfc89e0 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/balancer/TestBalancer.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/balancer/TestBalancer.java
@@ -26,8 +26,6 @@
 import java.util.Random;
 import java.util.concurrent.TimeoutException;
 
-import junit.framework.TestCase;
-
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.conf.Configuration;
@@ -46,11 +44,14 @@
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.DatanodeReportType;
 import org.apache.hadoop.hdfs.server.datanode.SimulatedFSDataset;
+import org.junit.Test;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
 
 /**
  * This class tests if a balancer schedules tasks correctly.
  */
-public class TestBalancer extends TestCase {
+public class TestBalancer {
   private static final Log LOG = LogFactory.getLog(
   "org.apache.hadoop.hdfs.TestBalancer");
   
@@ -365,8 +366,33 @@ public void integrationTest(Configuration conf) throws Exception {
     oneNodeTest(conf);
   }
   
+  /**
+   * Test parse method in Balancer#Cli class with threshold value out of
+   * boundaries.
+   */
+  @Test
+  public void testBalancerCliParseWithThresholdOutOfBoundaries() {
+    String parameters[] = new String[] { "-threshold", "0" };
+    String reason = "IllegalArgumentException is expected when threshold value"
+        + " is out of boundary.";
+    try {
+      Balancer.Cli.parse(parameters);
+      fail(reason);
+    } catch (IllegalArgumentException e) {
+      assertEquals("Number out of range: threshold = 0.0", e.getMessage());
+    }
+    parameters = new String[] { "-threshold", "101" };
+    try {
+      Balancer.Cli.parse(parameters);
+      fail(reason);
+    } catch (IllegalArgumentException e) {
+      assertEquals("Number out of range: threshold = 101.0", e.getMessage());
+    }
+  }
+  
   /** Test a cluster with even distribution, 
    * then a new empty node is added to the cluster*/
+  @Test
   public void testBalancer0() throws Exception {
     Configuration conf = new HdfsConfiguration();
     initConf(conf);
@@ -375,6 +401,7 @@ public void testBalancer0() throws Exception {
   }
 
   /** Test unevenly distributed cluster */
+  @Test
   public void testBalancer1() throws Exception {
     Configuration conf = new HdfsConfiguration();
     initConf(conf);
@@ -384,6 +411,7 @@ public void testBalancer1() throws Exception {
         new String[] {RACK0, RACK1});
   }
   
+  @Test
   public void testBalancer2() throws Exception {
     Configuration conf = new HdfsConfiguration();
     initConf(conf);