HDFS-6042. Fix rolling upgrade documentation and error messages. (Contributed by szetszwo)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1573785 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -134,3 +134,6 @@ HDFS-5535 subtasks:
     HDFS-6013. add rollingUpgrade information to latest UI.
     (Vinayakumar B via wheat9)
 
+    HDFS-6042. Fix rolling upgrade documentation and error messages. (szetszwo
+    via Arpit Agarwal)
+

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

@@ -50,7 +50,17 @@ public final class HdfsServerConstants {
   /** Startup options for rolling upgrade. */
   public static enum RollingUpgradeStartupOption{
     ROLLBACK, DOWNGRADE, STARTED;
-    
+
+    public String getOptionString() {
+      return StartupOption.ROLLINGUPGRADE.getName() + " "
+          + name().toLowerCase();
+    }
+
+    public boolean matches(StartupOption option) {
+      return option == StartupOption.ROLLINGUPGRADE
+          && option.getRollingUpgradeStartupOption() == this;
+    }
+
     private static final RollingUpgradeStartupOption[] VALUES = values();
 
     static RollingUpgradeStartupOption fromString(String s) {
@@ -87,24 +97,6 @@ public final class HdfsServerConstants {
     private static final Pattern ENUM_WITH_ROLLING_UPGRADE_OPTION = Pattern.compile(
         "(\\w+)\\((\\w+)\\)");
 
-    public static boolean isRollingUpgradeRollback(StartupOption option) {
-      return option == ROLLINGUPGRADE
-          && option.getRollingUpgradeStartupOption() 
-               == RollingUpgradeStartupOption.ROLLBACK;
-    }
-
-    public static boolean isRollingUpgradeDowngrade(StartupOption option) {
-      return option == ROLLINGUPGRADE
-          && 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

@@ -44,6 +44,7 @@ import org.apache.hadoop.hdfs.HAUtil;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.LayoutVersion;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NamenodeRole;
+import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.RollingUpgradeStartupOption;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.StartupOption;
 import org.apache.hadoop.hdfs.server.common.InconsistentFSStateException;
 import org.apache.hadoop.hdfs.server.common.Storage;
@@ -217,14 +218,18 @@ public class FSImage implements Closeable {
       NNStorage.checkVersionUpgradable(storage.getLayoutVersion());
     }
     if (startOpt != StartupOption.UPGRADE
-        && !StartupOption.isRollingUpgradeStarted(startOpt)
+        && !RollingUpgradeStartupOption.STARTED.matches(startOpt)
         && layoutVersion < Storage.LAST_PRE_UPGRADE_LAYOUT_VERSION
         && layoutVersion != HdfsConstants.NAMENODE_LAYOUT_VERSION) {
       throw new IOException(
           "\nFile system image contains an old layout version " 
           + storage.getLayoutVersion() + ".\nAn upgrade to version "
           + HdfsConstants.NAMENODE_LAYOUT_VERSION + " is required.\n"
-          + "Please restart NameNode with -upgrade option.");
+          + "Please restart NameNode with the \""
+          + RollingUpgradeStartupOption.STARTED.getOptionString()
+          + "\" option if a rolling upgraded is already started;"
+          + " or restart NameNode with the \""
+          + StartupOption.UPGRADE + "\" to start a new upgrade.");
     }
     
     storage.processStartupOptionsForUpgrade(startOpt, layoutVersion);
@@ -568,8 +573,8 @@ public class FSImage implements Closeable {
   private boolean loadFSImage(FSNamesystem target, StartupOption startOpt,
       MetaRecoveryContext recovery)
       throws IOException {
-    final boolean rollingRollback = StartupOption
-        .isRollingUpgradeRollback(startOpt);
+    final boolean rollingRollback
+        = RollingUpgradeStartupOption.ROLLBACK.matches(startOpt);
     final EnumSet<NameNodeFile> nnfs;
     if (rollingRollback) {
       // if it is rollback of rolling upgrade, only load from the rollback image
@@ -653,7 +658,7 @@ public class FSImage implements Closeable {
       long txnsAdvanced = loadEdits(editStreams, target, startOpt, recovery);
       needToSave |= needsResaveBasedOnStaleCheckpoint(imageFile.getFile(),
           txnsAdvanced);
-      if (StartupOption.isRollingUpgradeDowngrade(startOpt)) {
+      if (RollingUpgradeStartupOption.DOWNGRADE.matches(startOpt)) {
         // purge rollback image if it is downgrade
         archivalManager.purgeCheckpoints(NameNodeFile.IMAGE_ROLLBACK);
       }
@@ -724,8 +729,8 @@ public class FSImage implements Closeable {
       editLog.initJournalsForWrite();
       editLog.recoverUnclosedStreams();
     } else if (HAUtil.isHAEnabled(conf, nameserviceId)
-        && (startOpt == StartupOption.UPGRADE || StartupOption
-            .isRollingUpgradeRollback(startOpt))) {
+        && (startOpt == StartupOption.UPGRADE
+            || RollingUpgradeStartupOption.ROLLBACK.matches(startOpt))) {
       // This NN is HA, but we're doing an upgrade or a rollback of rolling
       // upgrade so init the edit log for write.
       editLog.initJournalsForWrite();

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

@@ -196,6 +196,7 @@ import org.apache.hadoop.hdfs.server.blockmanagement.OutOfV1GenerationStampsExce
 import org.apache.hadoop.hdfs.server.common.GenerationStamp;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.BlockUCState;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NamenodeRole;
+import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.RollingUpgradeStartupOption;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.StartupOption;
 import org.apache.hadoop.hdfs.server.common.Storage;
 import org.apache.hadoop.hdfs.server.common.Storage.StorageDirType;
@@ -891,7 +892,7 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
       MetaRecoveryContext recovery = startOpt.createRecoveryContext();
       final boolean staleImage
           = fsImage.recoverTransitionRead(startOpt, this, recovery);
-      if (StartupOption.isRollingUpgradeRollback(startOpt)) {
+      if (RollingUpgradeStartupOption.ROLLBACK.matches(startOpt)) {
         rollingUpgradeInfo = null;
       }
       final boolean needToSave = staleImage && !haEnabled && !isRollingUpgrade(); 

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

@@ -65,15 +65,16 @@
     The following are the steps for upgrading a HA cluster:
   </p>
   <ol>
-    <li>Prepare Rolling Upgrade<ul>
+    <li>Prepare Rolling Upgrade<ol>
       <li>Run "<code><a href="#dfsadmin_-rollingUpgrade">hdfs dfsadmin -rollingUpgrade prepare</a></code>"
         to create a fsimage for rollback.
       </li>
       <li>Run "<code><a href="#dfsadmin_-rollingUpgrade">hdfs dfsadmin -rollingUpgrade query</a></code>"
         to check the status of the rollback image.
-        Wait and re-run the command until the "Proceed with rolling upgrade" message is shown.
+        Wait and re-run the command until
+        the "<tt>Proceed with rolling upgrade</tt>" message is shown.
       </li>
-    </ul></li>
+    </ol></li>
     <li>Upgrade Active and Standby <em>NNs</em><ol>
       <li>Shutdown and upgrade <em>NN2</em>.</li>
       <li>Start <em>NN2</em> as standby with the
@@ -92,7 +93,7 @@
         <li>Run "<code><a href="#dfsadmin_-getDatanodeInfo">hdfs dfsadmin -getDatanodeInfo &lt;DATANODE_HOST:IPC_PORT&gt;</a></code>"
           to check and wait for the datanode to shutdown.</li>
         <li>Upgrade and restart the datanode.</li>
-        <li>Repeat the above steps for all the chosen datanodes in the subset.</li>
+        <li>Perform the above steps for all the chosen datanodes in the subset in parallel.</li>
       </ol>
       <li>Repeat the above steps until all datanodes in the cluster are upgraded.</li>
     </ol></li>
@@ -137,7 +138,7 @@
     <li>Upgrade <em>NN</em> and <em>SNN</em><ol>
       <li>Shutdown <em>SNN</em></li>
       <li>Shutdown and upgrade <em>NN</em>.</li>
-      <li>Start <em>NN</em> as standby with the
+      <li>Start <em>NN</em> with the
         "<a href="#namenode_-rollingUpgrade"><code>-rollingUpgrade started</code></a>" option.</li>
       <li>Upgrade and restart <em>SNN</em></li>
     </ol></li>
@@ -149,7 +150,7 @@
   <p>
     When the upgraded release is undesirable
     or, in some unlikely case, the upgrade fails (due to bugs in the newer release),
-    administrators may choose to downgrade HDFS back to the pre-upgrade release
+    administrators may choose to downgrade HDFS back to the pre-upgrade release,
     or rollback HDFS to the pre-upgrade release and the pre-upgrade state.
     Both downgrade and rollback require cluster downtime and are not done in a rolling fashion.
   </p>
@@ -157,8 +158,8 @@
     Note that downgrade and rollback are possible only after a rolling upgrade is started and
     before the upgrade is terminated.
     An upgrade can be terminated by either finalize, downgrade or rollback.
-    Therefore, it is impossible to run rollback after finalize or downgrade,
-    or to run downgrade after finalize.
+    Therefore, it may not be possible to perform rollback after finalize or downgrade,
+    or to perform downgrade after finalize.
   </p>
 
   <subsection name="Downgrade" id="Downgrade">