HDFS-6031. Add back the "-rollingUpgrade started" namenode startup option; otherwise, namenode cannot start when the layout version is changed.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1573040 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES_HDFS-5535.txt

@@ -33,7 +33,7 @@ HDFS-5535 subtasks:
     so that the standby namenode can create checkpoints during upgrade.
     (szetszwo & jing9)
 
-    HDFS-5535. Add BlockPoolSliceStorage 'trash' to handle block deletions
+    HDFS-5907. Add BlockPoolSliceStorage 'trash' to handle block deletions
     during rolling upgrades. (Arpit Agarwal)
 
     HDFS-5494. Merge Protobuf-based-FSImage code from trunk - fix build
@@ -123,3 +123,7 @@ HDFS-5535 subtasks:
 
     HDFS-6032. -rollingUpgrade query hits NPE after the NN restarts. (Haohui Mai
     via jing9)
+
+    HDFS-6031. Add back the "-rollingUpgrade started" namenode startup option;
+    otherwise, namenode cannot start when the layout version is changed.
+    (szetszwo)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/common/HdfsServerConstants.java

@@ -49,7 +49,7 @@ public final class HdfsServerConstants {
 
   /** Startup options for rolling upgrade. */
   public static enum RollingUpgradeStartupOption{
-    ROLLBACK, DOWNGRADE;
+    ROLLBACK, DOWNGRADE, STARTED;
     
     private static final RollingUpgradeStartupOption[] VALUES = values();
 
@@ -95,10 +95,16 @@ public final class HdfsServerConstants {
 
     public static boolean isRollingUpgradeDowngrade(StartupOption option) {
       return option == ROLLINGUPGRADE
-          && option.getRollingUpgradeStartupOption() 
+          && option.getRollingUpgradeStartupOption()
                == RollingUpgradeStartupOption.DOWNGRADE;
     }
 
+    public static boolean isRollingUpgradeStarted(StartupOption option) {
+      return option == ROLLINGUPGRADE
+          && option.getRollingUpgradeStartupOption() 
+               == RollingUpgradeStartupOption.STARTED;
+    }
+
     private final String name;
     
     // Used only with format and upgrade options

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImage.java

@@ -217,6 +217,7 @@ public class FSImage implements Closeable {
       NNStorage.checkVersionUpgradable(storage.getLayoutVersion());
     }
     if (startOpt != StartupOption.UPGRADE
+        && !StartupOption.isRollingUpgradeStarted(startOpt)
         && layoutVersion < Storage.LAST_PRE_UPGRADE_LAYOUT_VERSION
         && layoutVersion != HdfsConstants.NAMENODE_LAYOUT_VERSION) {
       throw new IOException(

hadoop-hdfs-project/hadoop-hdfs/src/site/xdoc/HdfsRollingUpgrade.xml

@@ -75,10 +75,14 @@
       </li>
     </ul></li>
     <li>Upgrade Active and Standby <em>NNs</em><ol>
-      <li>Shutdown, upgrade and restart <em>NN2</em> as standby.</li>
+      <li>Shutdown and upgrade <em>NN2</em>.</li>
+      <li>Start <em>NN2</em> as standby with the
+        "<a href="#namenode_-rollingUpgrade"><code>-rollingUpgrade started</code></a>" option.</li>
       <li>Failover from <em>NN1</em> to <em>NN2</em>
-       	so that <em>NN2</em> becomes active and <em>NN1</em> becomes standby.</li>
-      <li>Shutdown, upgrade and restart <em>NN1</em> as standby.</li>
+               so that <em>NN2</em> becomes active and <em>NN1</em> becomes standby.</li>
+      <li>Shutdown and upgrade <em>NN1</em>.</li>
+      <li>Start <em>NN1</em> as standby with the
+        "<a href="#namenode_-rollingUpgrade"><code>-rollingUpgrade started</code></a>" option.</li>
     </ol></li>
     <li>Upgrade <em>DNs</em><ol>
       <li>Choose a small subset of datanodes (e.g. all datanodes under a particular rack).</li>
@@ -132,7 +136,9 @@
   <ul>
     <li>Upgrade <em>NN</em> and <em>SNN</em><ol>
       <li>Shutdown <em>SNN</em></li>
-      <li>Shutdown, upgrade and restart <em>NN</em></li>
+      <li>Shutdown and upgrade <em>NN</em>.</li>
+      <li>Start <em>NN</em> as standby with the
+        "<a href="#namenode_-rollingUpgrade"><code>-rollingUpgrade started</code></a>" option.</li>
       <li>Upgrade and restart <em>SNN</em></li>
     </ol></li>
   </ul>
@@ -174,7 +180,7 @@
       <li>Shutdown all <em>NNs</em> and <em>DNs</em>.</li>
       <li>Restore the pre-upgrade release in all machines.</li>
       <li>Start <em>NNs</em> with the 
-	"<a href="#namenode_-rollingUpgrade"><code>-rollingUpgrade downgrade</code></a>" option.</li>
+        "<a href="#namenode_-rollingUpgrade"><code>-rollingUpgrade downgrade</code></a>" option.</li>
       <li>Start <em>DNs</em> normally.</li>
     </ol></li>
   </ul>
@@ -198,7 +204,7 @@
       <li>Shutdown all <em>NNs</em> and <em>DNs</em>.</li>
       <li>Restore the pre-upgrade release in all machines.</li>
       <li>Start <em>NNs</em> with the
-	"<a href="#namenode_-rollingUpgrade"><code>-rollingUpgrade rollback</code></a>" option.</li>
+        "<a href="#namenode_-rollingUpgrade"><code>-rollingUpgrade rollback</code></a>" option.</li>
       <li>Start <em>DNs</em> normally.</li>
     </ol></li>
   </ul>
@@ -248,9 +254,11 @@
   <subsection name="NameNode Startup Options" id="dfsadminCommands">
 
   <h4><code>namenode -rollingUpgrade</code></h4>
-  <source>hdfs namenode -rollingUpgrade &lt;downgrade|rollback&gt;</source>
+  <source>hdfs namenode -rollingUpgrade &lt;downgrade|rollback|started&gt;</source>
   <p>
-    Downgrade or rollback an ongoing rolling upgrade.
+    When a rolling upgrade is in progress,
+    the <code>-rollingUpgrade</code> namenode startup option is used to specify
+    various rolling upgrade options.
   </p>
     <ul><li>Options:<table>
       <tr><td><code>downgrade</code></td>
@@ -261,6 +269,11 @@
         <td>Restores the namenode back to the pre-upgrade release
             but also reverts the user data back to the pre-upgrade state.</td>
       </tr>
+      <tr><td><code>started</code></td>
+        <td>Specifies a rolling upgrade already started
+          so that the namenode should allow image directories
+          with different layout versions during startup.</td>
+      </tr>
     </table></li></ul>
 
   </subsection>