HDFS-5907. BlockPoolSliceStorage trash to handle block deletions during rolling upgrade. (Arpit Agarwal)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1568346 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -32,3 +32,7 @@ HDFS-5535 subtasks:
     HDFS-5889. When starting rolling upgrade, create a fs image for rollback
     so that the standby namenode can create checkpoints during upgrade.
     (szetszwo & jing9)
+
+    HDFS-5535. Add BlockPoolSliceStorage 'trash' to handle block deletions
+    during rolling upgrades. (Arpit Agarwal)
+

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

@@ -20,6 +20,8 @@ package org.apache.hadoop.hdfs.server.common;
 import java.io.DataInput;
 import java.io.DataOutput;
 import java.io.IOException;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.hdfs.server.namenode.MetaRecoveryContext;
@@ -81,7 +83,10 @@ public final class HdfsServerConstants {
     FORCE("-force"),
     NONINTERACTIVE("-nonInteractive"),
     RENAMERESERVED("-renameReserved");
-    
+
+    private static final Pattern ENUM_WITH_ROLLING_UPGRADE_OPTION = Pattern.compile(
+        "(\\w+)\\((\\w+)\\)");
+
     private final String name;
     
     // Used only with format and upgrade options
@@ -167,6 +172,17 @@ public final class HdfsServerConstants {
       }
       return super.toString();
     }
+
+    static public StartupOption getEnum(String value) {
+      Matcher matcher = ENUM_WITH_ROLLING_UPGRADE_OPTION.matcher(value);
+      if (matcher.matches()) {
+        StartupOption option = StartupOption.valueOf(matcher.group(1));
+        option.setRollingUpgradeStartupOption(matcher.group(2));
+        return option;
+      } else {
+        return StartupOption.valueOf(value);
+      }
+    }
   }
 
   // Timeouts for communicating with DataNode for streaming writes/reads

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BPOfferService.java

@@ -413,6 +413,18 @@ class BPOfferService {
     return Lists.newArrayList(bpServices);
   }
   
+  /**
+   * Signal the current rolling upgrade status as indicated by the NN.
+   * @param inProgress true if a rolling upgrade is in progress
+   */
+  void signalRollingUpgrade(boolean inProgress) {
+    if (inProgress) {
+      dn.getFSDataset().enableDeleteToTrash(getBlockPoolId());
+    } else {
+      dn.getFSDataset().disableAndPurgeTrashStorage(getBlockPoolId());
+    }
+  }
+
   /**
    * Update the BPOS's view of which NN is active, based on a heartbeat
    * response from one of the actors.
@@ -611,7 +623,8 @@ class BPOfferService {
       // See HDFS-2987.
       throw new UnsupportedOperationException("Received unimplemented DNA_SHUTDOWN");
     case DatanodeProtocol.DNA_FINALIZE:
-      String bp = ((FinalizeCommand) cmd).getBlockPoolId(); 
+      String bp = ((FinalizeCommand) cmd).getBlockPoolId();
+      LOG.info("Got finalize command for block pool " + bp);
       assert getBlockPoolId().equals(bp) :
         "BP " + getBlockPoolId() + " received DNA_FINALIZE " +
         "for other block pool " + bp;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BPServiceActor.java

@@ -33,8 +33,8 @@ import org.apache.hadoop.hdfs.StorageType;
 import org.apache.hadoop.hdfs.protocol.BlockListAsLongs;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
 import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
-import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
+import org.apache.hadoop.hdfs.protocol.RollingUpgradeStatus;
 import org.apache.hadoop.hdfs.protocol.UnregisteredNodeException;
 import org.apache.hadoop.hdfs.protocolPB.DatanodeProtocolClientSideTranslatorPB;
 import org.apache.hadoop.hdfs.server.common.IncorrectVersionException;
@@ -611,6 +611,20 @@ class BPServiceActor implements Runnable {
     bpos.shutdownActor(this);
   }
 
+  private void handleRollingUpgradeStatus(HeartbeatResponse resp) {
+    RollingUpgradeStatus rollingUpgradeStatus = resp.getRollingUpdateStatus();
+    if (rollingUpgradeStatus != null &&
+        rollingUpgradeStatus.getBlockPoolId().compareTo(bpos.getBlockPoolId()) != 0) {
+      // Can this ever occur?
+      LOG.error("Invalid BlockPoolId " +
+          rollingUpgradeStatus.getBlockPoolId() +
+          " in HeartbeatResponse. Expected " +
+          bpos.getBlockPoolId());
+    } else {
+      bpos.signalRollingUpgrade(rollingUpgradeStatus != null);
+    }
+  }
+
   /**
    * Main loop for each BP thread. Run until shutdown,
    * forever calling remote NameNode functions.
@@ -657,6 +671,10 @@ class BPServiceActor implements Runnable {
                 this, resp.getNameNodeHaState());
             state = resp.getNameNodeHaState().getState();
 
+            if (state == HAServiceState.ACTIVE) {
+              handleRollingUpgradeStatus(resp);
+            }
+
             long startProcessCommands = now();
             if (!processCommand(resp.getCommands()))
               continue;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockPoolSliceStorage.java

@@ -27,11 +27,13 @@ import java.util.Properties;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
+import com.google.common.annotations.VisibleForTesting;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.fs.FileUtil;
 import org.apache.hadoop.fs.HardLink;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.LayoutVersion;
+import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.RollingUpgradeStartupOption;
 import org.apache.hadoop.hdfs.server.common.InconsistentFSStateException;
 import org.apache.hadoop.hdfs.server.common.Storage;
 import org.apache.hadoop.hdfs.server.common.StorageInfo;
@@ -57,9 +59,19 @@ import org.apache.hadoop.util.Daemon;
  */
 @InterfaceAudience.Private
 public class BlockPoolSliceStorage extends Storage {
-  private static final Pattern BLOCK_POOL_PATH_PATTERN = Pattern
-      .compile("^(.*)"
-          + "(\\/BP-[0-9]+\\-\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\-[0-9]+\\/.*)$");
+  static final String TRASH_ROOT_DIR = "trash";
+
+  private static final String BLOCK_POOL_ID_PATTERN_BASE =
+      "/BP-\\d+-\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}-\\d+/";
+
+  private static final Pattern BLOCK_POOL_PATH_PATTERN = Pattern.compile(
+      "^(.*)(" + BLOCK_POOL_ID_PATTERN_BASE + ")(.*)$");
+
+  private static final Pattern BLOCK_POOL_CURRENT_PATH_PATTERN = Pattern.compile(
+      "^(.*)(" + BLOCK_POOL_ID_PATTERN_BASE + ")(" + STORAGE_DIR_CURRENT + ")(.*)$");
+
+  private static final Pattern BLOCK_POOL_TRASH_PATH_PATTERN = Pattern.compile(
+      "^(.*)(" + BLOCK_POOL_ID_PATTERN_BASE + ")(" + TRASH_ROOT_DIR + ")(.*)$");
 
   private String blockpoolID = ""; // id of the blockpool
 
@@ -92,6 +104,7 @@ public class BlockPoolSliceStorage extends Storage {
    */
   void recoverTransitionRead(DataNode datanode, NamespaceInfo nsInfo,
       Collection<File> dataDirs, StartupOption startOpt) throws IOException {
+    LOG.info("Analyzing storage directories for bpid " + nsInfo.getBlockPoolID());
     // 1. For each BP data directory analyze the state and
     // check whether all is consistent before transitioning.
     this.storageDirs = new ArrayList<StorageDirectory>(dataDirs.size());
@@ -231,8 +244,15 @@ public class BlockPoolSliceStorage extends Storage {
    */
   private void doTransition(StorageDirectory sd,
       NamespaceInfo nsInfo, StartupOption startOpt) throws IOException {
-    if (startOpt == StartupOption.ROLLBACK)
+    if (startOpt == StartupOption.ROLLBACK) {
       doRollback(sd, nsInfo); // rollback if applicable
+    } else if (startOpt == StartupOption.ROLLINGUPGRADE &&
+        startOpt.getRollingUpgradeStartupOption() == RollingUpgradeStartupOption.ROLLBACK) {
+      File trashRoot = getTrashRootDir(sd);
+      int filesRestored =
+          trashRoot.exists() ? restoreBlockFilesFromTrash(trashRoot) : 0;
+      LOG.info("Restored " + filesRestored + " block files from trash.");
+    }
     
     readProperties(sd);
     checkVersionUpgradable(this.layoutVersion);
@@ -358,6 +378,34 @@ public class BlockPoolSliceStorage extends Storage {
     }
   }
 
+  /**
+   * Restore all files from the trash directory to their corresponding
+   * locations under current/
+   *
+   * @param trashRoot
+   */
+  private int restoreBlockFilesFromTrash(File trashRoot) {
+    int filesRestored = 0;
+    File restoreDirectory = null;
+
+    for (File child : trashRoot.listFiles()) {
+      if (child.isDirectory()) {
+        // Recurse to process subdirectories.
+        filesRestored += restoreBlockFilesFromTrash(child);
+      }
+
+      if (restoreDirectory == null) {
+        restoreDirectory = new File(getRestoreDirectory(child));
+        restoreDirectory.mkdirs();
+      }
+
+      child.renameTo(new File(restoreDirectory, child.getName()));
+      ++filesRestored;
+    }
+
+    return filesRestored;
+  }
+
   /*
    * Roll back to old snapshot at the block pool level
    * If previous directory exists: 
@@ -505,4 +553,51 @@ public class BlockPoolSliceStorage extends Storage {
   public boolean isPreUpgradableLayout(StorageDirectory sd) throws IOException {
     return false;
   }
+
+  private File getTrashRootDir(StorageDirectory sd) {
+    return new File(sd.getRoot(), TRASH_ROOT_DIR);
+  }
+
+  /**
+   * Get a target subdirectory under trash/ for a given block file that is being
+   * deleted.
+   *
+   * The subdirectory structure under trash/ mirrors that under current/ to keep
+   * implicit memory of where the files are to be restored (if necessary).
+   *
+   * @param blockFile
+   * @return the trash directory for a given block file that is being deleted.
+   */
+  public String getTrashDirectory(File blockFile) {
+    Matcher matcher = BLOCK_POOL_CURRENT_PATH_PATTERN.matcher(blockFile.getParent());
+    String trashDirectory = matcher.replaceFirst("$1$2" + TRASH_ROOT_DIR + "$4");
+    return trashDirectory;
+  }
+
+  /**
+   * Get a target subdirectory under current/ for a given block file that is being
+   * restored from trash.
+   *
+   * The subdirectory structure under trash/ mirrors that under current/ to keep
+   * implicit memory of where the files are to be restored.
+   *
+   * @param blockFile
+   * @return the target directory to restore a previously deleted block file.
+   */
+  @VisibleForTesting
+  String getRestoreDirectory(File blockFile) {
+    Matcher matcher = BLOCK_POOL_TRASH_PATH_PATTERN.matcher(blockFile.getParent());
+    String restoreDirectory = matcher.replaceFirst("$1$2" + STORAGE_DIR_CURRENT + "$4");
+    LOG.info("Restoring " + blockFile + " to " + restoreDirectory);
+    return restoreDirectory;
+  }
+
+  /**
+   * Delete all files and directories in the trash directories.
+   */
+  public void emptyTrash() {
+    for (StorageDirectory sd : storageDirs) {
+      FileUtil.fullyDelete(getTrashRootDir(sd));
+    }
+  }
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java

@@ -101,6 +101,7 @@ import org.apache.hadoop.hdfs.security.token.block.ExportedBlockKeys;
 import org.apache.hadoop.hdfs.security.token.block.InvalidBlockTokenException;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.ReplicaState;
+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.JspHelper;
 import org.apache.hadoop.hdfs.server.common.StorageInfo;
@@ -210,7 +211,14 @@ public class DataNode extends Configured
   static final Log ClientTraceLog =
     LogFactory.getLog(DataNode.class.getName() + ".clienttrace");
   
-  private static final String USAGE = "Usage: java DataNode [-rollback | -regular]";
+  private static final String USAGE =
+      "Usage: java DataNode [-regular | -rollback | -rollingupgrade rollback]\n" +
+      "    -regular                 : Normal DataNode startup (default).\n" +
+      "    -rollback                : Rollback a standard upgrade.\n" +
+      "    -rollingupgrade rollback : Rollback a rolling upgrade operation.\n" +
+      "  Refer to HDFS documentation for the difference between standard\n" +
+      "  and rolling upgrades.";
+
   static final int CURRENT_BLOCK_FORMAT_VERSION = 1;
 
   /**
@@ -1754,6 +1762,7 @@ public class DataNode extends Configured
     }
     
     if (!parseArguments(args, conf)) {
+      LOG.error("Bad command line arguments");
       printUsage(System.err);
       return null;
     }
@@ -1788,6 +1797,7 @@ public class DataNode extends Configured
   /** Instantiate & Start a single datanode daemon and wait for it to finish.
    *  If this thread is specifically interrupted, it will stop waiting.
    */
+  @VisibleForTesting
   public static DataNode createDataNode(String args[],
                                  Configuration conf) throws IOException {
     return createDataNode(args, conf, null);
@@ -1796,6 +1806,7 @@ public class DataNode extends Configured
   /** Instantiate & Start a single datanode daemon and wait for it to finish.
    *  If this thread is specifically interrupted, it will stop waiting.
    */
+  @VisibleForTesting
   @InterfaceAudience.Private
   public static DataNode createDataNode(String args[], Configuration conf,
       SecureResources resources) throws IOException {
@@ -1906,25 +1917,40 @@ public class DataNode extends Configured
    *
    * @return false if passed argements are incorrect
    */
-  private static boolean parseArguments(String args[], 
-                                        Configuration conf) {
-    int argsLen = (args == null) ? 0 : args.length;
+  @VisibleForTesting
+  static boolean parseArguments(String args[], Configuration conf) {
     StartupOption startOpt = StartupOption.REGULAR;
-    for(int i=0; i < argsLen; i++) {
-      String cmd = args[i];
+    int i = 0;
+
+    if (args != null && args.length != 0) {
+      String cmd = args[i++];
       if ("-r".equalsIgnoreCase(cmd) || "--rack".equalsIgnoreCase(cmd)) {
         LOG.error("-r, --rack arguments are not supported anymore. RackID " +
             "resolution is handled by the NameNode.");
-        terminate(1);
-      } else if ("-rollback".equalsIgnoreCase(cmd)) {
+        return false;
+      } else if (StartupOption.ROLLBACK.getName().equalsIgnoreCase(cmd)) {
         startOpt = StartupOption.ROLLBACK;
-      } else if ("-regular".equalsIgnoreCase(cmd)) {
+      } else if (StartupOption.REGULAR.getName().equalsIgnoreCase(cmd)) {
         startOpt = StartupOption.REGULAR;
-      } else
+      } else if (StartupOption.ROLLINGUPGRADE.getName().equalsIgnoreCase(cmd)) {
+        startOpt = StartupOption.ROLLINGUPGRADE;
+
+        if ((i < args.length ) &&
+            (args[i].equalsIgnoreCase(RollingUpgradeStartupOption.ROLLBACK.toString()))) {
+          startOpt.setRollingUpgradeStartupOption(args[i++]);
+        } else {
+          LOG.error("Missing or unrecognized option to " + StartupOption.ROLLINGUPGRADE);
+          return false;
+        }
+
+        LOG.info("Rolling upgrade rollback requested via startup option");
+      } else {
         return false;
+      }
     }
+
     setStartupOption(conf, startOpt);
-    return true;
+    return (args == null || i == args.length);    // Fail if more than one cmd specified!
   }
 
   private static void setStartupOption(Configuration conf, StartupOption opt) {
@@ -1932,8 +1958,9 @@ public class DataNode extends Configured
   }
 
   static StartupOption getStartupOption(Configuration conf) {
-    return StartupOption.valueOf(conf.get(DFS_DATANODE_STARTUP_KEY,
-                                          StartupOption.REGULAR.toString()));
+    String value = conf.get(DFS_DATANODE_STARTUP_KEY,
+                            StartupOption.REGULAR.toString());
+    return StartupOption.getEnum(value);
   }
 
   /**
@@ -1963,11 +1990,15 @@ public class DataNode extends Configured
 
 
   public static void secureMain(String args[], SecureResources resources) {
+    int errorCode = 0;
     try {
       StringUtils.startupShutdownMessage(DataNode.class, args, LOG);
       DataNode datanode = createDataNode(args, null, resources);
-      if (datanode != null)
+      if (datanode != null) {
         datanode.join();
+      } else {
+        errorCode = 1;
+      }
     } catch (Throwable e) {
       LOG.fatal("Exception in secureMain", e);
       terminate(1, e);
@@ -1977,7 +2008,7 @@ public class DataNode extends Configured
       // condition was not met. Also, In secure mode, control will go to Jsvc
       // and Datanode process hangs if it does not exit.
       LOG.warn("Exiting Datanode");
-      terminate(0);
+      terminate(errorCode);
     }
   }
   

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataStorage.java

@@ -25,6 +25,7 @@ import java.io.IOException;
 import java.io.RandomAccessFile;
 import java.nio.channels.FileLock;
 import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
 
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
@@ -65,6 +66,13 @@ public class DataStorage extends Storage {
   public final static String STORAGE_DIR_FINALIZED = "finalized";
   public final static String STORAGE_DIR_TMP = "tmp";
 
+  // Set of bpids for which 'trash' is currently enabled.
+  // When trash is enabled block files are moved under a separate
+  // 'trash' folder instead of being deleted right away. This can
+  // be useful during rolling upgrades, for example.
+  // The set is backed by a concurrent HashMap.
+  private Set<String> trashEnabledBpids;
+
   /**
    * Datanode UUID that this storage is currently attached to. This
    *  is the same as the legacy StorageID for datanodes that were
@@ -83,6 +91,8 @@ public class DataStorage extends Storage {
 
   DataStorage() {
     super(NodeType.DATA_NODE);
+    trashEnabledBpids = Collections.newSetFromMap(
+        new ConcurrentHashMap<String, Boolean>());
   }
   
   public StorageInfo getBPStorage(String bpid) {
@@ -107,6 +117,49 @@ public class DataStorage extends Storage {
       sd.setStorageUuid(DatanodeStorage.generateUuid());
     }
   }
+
+  /**
+   * Enable trash for the specified block pool storage.
+   *
+   * @param bpid
+   * @param  inProgress
+   */
+  public void enableTrash(String bpid) {
+    if (trashEnabledBpids.add(bpid)) {
+      LOG.info("Enabled trash for bpid " + bpid);
+    }
+  }
+
+  /**
+   * Disable trash for the specified block pool storage.
+   * Existing files in trash are purged i.e. permanently deleted.
+   *
+   * @param bpid
+   * @param  inProgress
+   */
+  public void disableAndPurgeTrash(String bpid) {
+    if (trashEnabledBpids.remove(bpid)) {
+      LOG.info("Disabled trash for bpid " + bpid);
+    }
+    ((BlockPoolSliceStorage) getBPStorage(bpid)).emptyTrash();
+  }
+
+  /**
+   * If rolling upgrades are in progress then do not delete block files
+   * immediately. Instead we move the block files to an intermediate
+   * 'trash' directory. If there is a subsequent rollback, then the block
+   * files will be restored from trash.
+   *
+   * @param blockFile
+   * @return trash directory if rolling upgrade is in progress, null
+   *         otherwise.
+   */
+  public String getTrashDirectoryForBlockFile(String bpid, File blockFile) {
+    if (trashEnabledBpids.contains(bpid)) {
+      return ((BlockPoolSliceStorage) getBPStorage(bpid)).getTrashDirectory(blockFile);
+    }
+    return null;
+  }
   
   /**
    * Analyze storage directories.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/FsDatasetSpi.java

@@ -411,5 +411,17 @@ public interface FsDatasetSpi<V extends FsVolumeSpi> extends FSDatasetMBean {
    */
   public HdfsBlocksMetadata getHdfsBlocksMetadata(List<ExtendedBlock> blocks)
       throws IOException;
+
+  /**
+   * Enable 'trash' for the given dataset. When trash is enabled, files are
+   * moved to a separate trash directory instead of being deleted immediately.
+   * This can be useful for example during rolling upgrades.
+   */
+  public void enableDeleteToTrash(String bpid);
+
+  /**
+   * Disable 'trash' for the given dataset and purge existing files in 'trash'.
+   */
+  public void disableAndPurgeTrashStorage(String bpid);
 }
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsDatasetAsyncDiskService.java

@@ -153,29 +153,34 @@ class FsDatasetAsyncDiskService {
    * dfsUsed statistics accordingly.
    */
   void deleteAsync(FsVolumeImpl volume, File blockFile, File metaFile,
-      ExtendedBlock block) {
+      ExtendedBlock block, String trashDirectory) {
     LOG.info("Scheduling " + block.getLocalBlock()
         + " file " + blockFile + " for deletion");
     ReplicaFileDeleteTask deletionTask = new ReplicaFileDeleteTask(
-        volume, blockFile, metaFile, block);
+        volume, blockFile, metaFile, block, trashDirectory);
     execute(volume.getCurrentDir(), deletionTask);
   }
   
   /** A task for deleting a block file and its associated meta file, as well
-   *  as decrement the dfs usage of the volume. 
+   *  as decrement the dfs usage of the volume.
+   *  Optionally accepts a trash directory. If one is specified then the files
+   *  are moved to trash instead of being deleted. If none is specified then the
+   *  files are deleted immediately.
    */
   class ReplicaFileDeleteTask implements Runnable {
     final FsVolumeImpl volume;
     final File blockFile;
     final File metaFile;
     final ExtendedBlock block;
+    final String trashDirectory;
     
     ReplicaFileDeleteTask(FsVolumeImpl volume, File blockFile,
-        File metaFile, ExtendedBlock block) {
+        File metaFile, ExtendedBlock block, String trashDirectory) {
       this.volume = volume;
       this.blockFile = blockFile;
       this.metaFile = metaFile;
       this.block = block;
+      this.trashDirectory = trashDirectory;
     }
 
     @Override
@@ -186,12 +191,34 @@ class FsDatasetAsyncDiskService {
           + " and meta file " + metaFile + " from volume " + volume;
     }
 
+    private boolean deleteFiles() {
+      return blockFile.delete() && (metaFile.delete() || !metaFile.exists());
+    }
+
+    private boolean moveFiles() {
+      File newBlockFile = new File(trashDirectory, blockFile.getName());
+      File newMetaFile = new File(trashDirectory, metaFile.getName());
+      (new File(trashDirectory)).mkdirs();
+
+      if (LOG.isDebugEnabled()) {
+        LOG.debug("Moving files " + blockFile.getName() + " and " +
+            metaFile.getName() + " to trash.");
+      }
+      return (blockFile.renameTo(newBlockFile) &&
+              metaFile.renameTo(newMetaFile));
+    }
+
     @Override
     public void run() {
       long dfsBytes = blockFile.length() + metaFile.length();
-      if (!blockFile.delete() || (!metaFile.delete() && metaFile.exists())) {
-        LOG.warn("Unexpected error trying to delete block "
-            + block.getBlockPoolId() + " " + block.getLocalBlock()
+      boolean result;
+
+      result = (trashDirectory == null) ? deleteFiles() : moveFiles();
+
+      if (!result) {
+        LOG.warn("Unexpected error trying to "
+            + (trashDirectory == null ? "delete" : "move")
+            + " block " + block.getBlockPoolId() + " " + block.getLocalBlock()
             + " at file " + blockFile + ". Ignored.");
       } else {
         if(block.getLocalBlock().getNumBytes() != BlockCommand.NO_ACK){

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsDatasetImpl.java

@@ -38,7 +38,6 @@ import javax.management.NotCompliantMBeanException;
 import javax.management.ObjectName;
 import javax.management.StandardMBean;
 
-import com.google.common.base.Preconditions;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.classification.InterfaceAudience;
@@ -193,6 +192,7 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
   }
     
   final DataNode datanode;
+  final DataStorage dataStorage;
   final FsVolumeList volumes;
   final FsDatasetAsyncDiskService asyncDiskService;
   final FsDatasetCache cacheManager;
@@ -209,6 +209,7 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
   FsDatasetImpl(DataNode datanode, DataStorage storage, Configuration conf
       ) throws IOException {
     this.datanode = datanode;
+    this.dataStorage = storage;
     // The number of volumes required for operation is the total number 
     // of volumes minus the number of failed volumes we can tolerate.
     final int volFailuresTolerated =
@@ -1234,7 +1235,8 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
       // finishes.
       asyncDiskService.deleteAsync(v, f,
           FsDatasetUtil.getMetaFile(f, invalidBlks[i].getGenerationStamp()),
-          new ExtendedBlock(bpid, invalidBlks[i]));
+          new ExtendedBlock(bpid, invalidBlks[i]),
+          dataStorage.getTrashDirectoryForBlockFile(bpid, f));
     }
     if (error) {
       throw new IOException("Error in deleting blocks.");
@@ -1891,6 +1893,16 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
         blocksVolumeIds, blocksVolumeIndexes);
   }
 
+  @Override
+  public void enableDeleteToTrash(String bpid) {
+    dataStorage.enableTrash(bpid);
+  }
+
+  @Override
+  public void disableAndPurgeTrashStorage(String bpid) {
+    dataStorage.disableAndPurgeTrash(bpid);
+  }
+
   @Override
   public RollingLogs createRollingLogs(String bpid, String prefix
       ) throws IOException {

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/MiniDFSCluster.java

@@ -391,6 +391,10 @@ public class MiniDFSCluster {
       this.dnArgs = args;
       this.secureResources = secureResources;
     }
+
+    public void setDnArgs(String ... args) {
+      dnArgs = args;
+    }
   }
 
   private Configuration conf;

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/SimulatedFSDataset.java

@@ -1040,6 +1040,16 @@ public class SimulatedFSDataset implements FsDatasetSpi<FsVolumeSpi> {
     throw new UnsupportedOperationException();
   }
 
+  @Override
+  public void enableDeleteToTrash(String bpid) {
+    throw new UnsupportedOperationException();
+  }
+
+  @Override
+  public void disableAndPurgeTrashStorage(String bpid) {
+    throw new UnsupportedOperationException();
+  }
+
   @Override
   public void checkAndUpdate(String bpid, long blockId, File diskFile,
       File diskMetaFile, FsVolumeSpi vol) {