diff --git a/hadoop-mapreduce-project/CHANGES.txt b/hadoop-mapreduce-project/CHANGES.txt
index 42f7635d73..7b0ab61a4a 100644
--- a/hadoop-mapreduce-project/CHANGES.txt
+++ b/hadoop-mapreduce-project/CHANGES.txt
@@ -193,6 +193,8 @@ Branch-2 ( Unreleased changes )
     MAPREDUCE-4610. Support deprecated mapreduce.job.counters.limit property in
     MR2. (tomwhite)
 
+    MAPREDUCE-4629. Remove JobHistory.DEBUG_MODE (Karthik Kambatla via bobby)
+
 Release 2.1.0-alpha - Unreleased 
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-common/src/main/java/org/apache/hadoop/mapreduce/v2/jobhistory/JHAdminConfig.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-common/src/main/java/org/apache/hadoop/mapreduce/v2/jobhistory/JHAdminConfig.java
index 20f3a89b6d..fe6b134fe5 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-common/src/main/java/org/apache/hadoop/mapreduce/v2/jobhistory/JHAdminConfig.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-common/src/main/java/org/apache/hadoop/mapreduce/v2/jobhistory/JHAdminConfig.java
@@ -61,11 +61,6 @@ public class JHAdminConfig {
     MR_HISTORY_PREFIX + "datestring.cache.size";
   public static final int DEFAULT_MR_HISTORY_DATESTRING_CACHE_SIZE = 200000;
   
-  //TODO REMOVE debug-mode
-  /** Equivalent to 0.20 mapreduce.jobhistory.debug.mode */
-  public static final String MR_HISTORY_DEBUG_MODE = 
-    MR_HISTORY_PREFIX + "debug-mode";
-  
   /** Path where history files should be stored for DONE jobs. **/
   public static final String MR_HISTORY_DONE_DIR =
     MR_HISTORY_PREFIX + "done-dir";
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-common/src/main/java/org/apache/hadoop/mapreduce/v2/jobhistory/JobHistoryUtils.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-common/src/main/java/org/apache/hadoop/mapreduce/v2/jobhistory/JobHistoryUtils.java
index 38004cc6a7..272641ecae 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-common/src/main/java/org/apache/hadoop/mapreduce/v2/jobhistory/JobHistoryUtils.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-common/src/main/java/org/apache/hadoop/mapreduce/v2/jobhistory/JobHistoryUtils.java
@@ -343,20 +343,19 @@ public static String historyLogSubdirectory(JobId id, String timestampComponent,
   /**
    * Gets the timestamp component based on millisecond time.
    * @param millisecondTime
-   * @param debugMode
    * @return the timestamp component based on millisecond time
    */
-  public static String timestampDirectoryComponent(long millisecondTime, boolean debugMode) {
+  public static String timestampDirectoryComponent(long millisecondTime) {
     Calendar timestamp = Calendar.getInstance();
     timestamp.setTimeInMillis(millisecondTime);
     String dateString = null;
-    dateString = String.format(
-        TIMESTAMP_DIR_FORMAT,
-        timestamp.get(Calendar.YEAR),
-        // months are 0-based in Calendar, but people will expect January
-        // to be month #1.
-        timestamp.get(debugMode ? Calendar.HOUR : Calendar.MONTH) + 1,
-        timestamp.get(debugMode ? Calendar.MINUTE : Calendar.DAY_OF_MONTH));
+    dateString = String
+        .format(TIMESTAMP_DIR_FORMAT,
+            timestamp.get(Calendar.YEAR),
+            // months are 0-based in Calendar, but people will expect January to
+            // be month #1.
+            timestamp.get(Calendar.MONTH) + 1,
+            timestamp.get(Calendar.DAY_OF_MONTH));
     dateString = dateString.intern();
     return dateString;
   }
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-hs/src/main/java/org/apache/hadoop/mapreduce/v2/hs/HistoryFileManager.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-hs/src/main/java/org/apache/hadoop/mapreduce/v2/hs/HistoryFileManager.java
index bc18646712..6779588859 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-hs/src/main/java/org/apache/hadoop/mapreduce/v2/hs/HistoryFileManager.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-hs/src/main/java/org/apache/hadoop/mapreduce/v2/hs/HistoryFileManager.java
@@ -358,7 +358,6 @@ public synchronized Configuration loadConfFile() throws IOException {
 
   private Configuration conf;
 
-  private boolean debugMode;
   private String serialNumberFormat;
 
   private Path doneDirPrefixPath = null; // folder for completed jobs
@@ -379,8 +378,7 @@ public HistoryFileManager() {
   public void init(Configuration conf) {
     this.conf = conf;
 
-    debugMode = conf.getBoolean(JHAdminConfig.MR_HISTORY_DEBUG_MODE, false);
-    int serialNumberLowDigits = debugMode ? 1 : 3;
+    int serialNumberLowDigits = 3;
     serialNumberFormat = ("%0"
         + (JobHistoryUtils.SERIAL_NUMBER_DIRECTORY_DIGITS + serialNumberLowDigits)
         + "d");
@@ -780,8 +778,8 @@ private Path canonicalHistoryLogPath(JobId id, String timestampComponent) {
   }
 
   private Path canonicalHistoryLogPath(JobId id, long millisecondTime) {
-    String timestampComponent = JobHistoryUtils.timestampDirectoryComponent(
-        millisecondTime, debugMode);
+    String timestampComponent = JobHistoryUtils
+        .timestampDirectoryComponent(millisecondTime);
     return new Path(doneDirPrefixPath, JobHistoryUtils.historyLogSubdirectory(
         id, timestampComponent, serialNumberFormat));
   }