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Subject: svn commit: r1091131 - in /hadoop/hdfs/trunk: ./
 src/java/org/apache/hadoop/hdfs/protocol/
 src/java/org/apache/hadoop/hdfs/server/namenode/
 src/java/org/apache/hadoop/hdfs/tools/offlineEditsViewer/
 src/java/org/apache/hadoop/hdfs/tools/offlineImageView...
Date: Mon, 11 Apr 2011 17:15:28 -0000
To: hdfs-commits@hadoop.apache.org
From: hairong@apache.org
Message-Id: <20110411171528.6BE3A23889B1@eris.apache.org>

Author: hairong
Date: Mon Apr 11 17:15:27 2011
New Revision: 1091131

URL: http://svn.apache.org/viewvc?rev=1091131&view=rev
Log:
HDFS-1630. Support fsedits checksum. Contrbuted by Hairong Kuang.

Modified:
    hadoop/hdfs/trunk/CHANGES.txt
    hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/protocol/FSConstants.java
    hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/BackupImage.java
    hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/EditLogFileOutputStream.java
    hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/FSEditLog.java
    hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/FSEditLogLoader.java
    hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/tools/offlineEditsViewer/EditsElement.java
    hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/tools/offlineEditsViewer/EditsLoaderCurrent.java
    hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/tools/offlineImageViewer/ImageLoaderCurrent.java
    hadoop/hdfs/trunk/src/test/hdfs/org/apache/hadoop/hdfs/server/namenode/TestEditLog.java

Modified: hadoop/hdfs/trunk/CHANGES.txt
URL: http://svn.apache.org/viewvc/hadoop/hdfs/trunk/CHANGES.txt?rev=1091131&r1=1091130&r2=1091131&view=diff
==============================================================================
--- hadoop/hdfs/trunk/CHANGES.txt (original)
+++ hadoop/hdfs/trunk/CHANGES.txt Mon Apr 11 17:15:27 2011
@@ -25,6 +25,8 @@ Trunk (unreleased changes)
     for transferring RBW/Finalized with acknowledgement and without using RPC.
     (szetszwo)
 
+    HDFS_1630. Support fsedits checksum. (hairong)
+
   IMPROVEMENTS
 
     HDFS-1510. Added test-patch.properties required by test-patch.sh (nigel)

Modified: hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/protocol/FSConstants.java
URL: http://svn.apache.org/viewvc/hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/protocol/FSConstants.java?rev=1091131&r1=1091130&r2=1091131&view=diff
==============================================================================
--- hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/protocol/FSConstants.java (original)
+++ hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/protocol/FSConstants.java Mon Apr 11 17:15:27 2011
@@ -88,7 +88,7 @@ public interface FSConstants {
   // Version is reflected in the data storage file.
   // Versions are negative.
   // Decrement LAYOUT_VERSION to define a new version.
-  public static final int LAYOUT_VERSION = -27;
+  public static final int LAYOUT_VERSION = -28;
   // Current version: 
-  // -27: remove intentionally corrupt pre-0.13 image directory
+  // -28: Support fsedits checksum
 }

Modified: hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/BackupImage.java
URL: http://svn.apache.org/viewvc/hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/BackupImage.java?rev=1091131&r1=1091130&r2=1091131&view=diff
==============================================================================
--- hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/BackupImage.java (original)
+++ hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/BackupImage.java Mon Apr 11 17:15:27 2011
@@ -17,12 +17,15 @@
  */
 package org.apache.hadoop.hdfs.server.namenode;
 
+import java.io.BufferedInputStream;
 import java.io.DataInputStream;
 import java.io.File;
 import java.io.IOException;
 import java.net.URI;
 import java.util.Collection;
 import java.util.Iterator;
+import java.util.zip.CheckedInputStream;
+import java.util.zip.Checksum;
 
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.hdfs.server.common.HdfsConstants;
@@ -226,8 +229,15 @@ public class BackupImage extends FSImage
           // update NameSpace in memory
           backupInputStream.setBytes(data);
           FSEditLogLoader logLoader = new FSEditLogLoader(namesystem);
-          logLoader.loadEditRecords(storage.getLayoutVersion(),
-                    backupInputStream.getDataInputStream(), true);
+          int logVersion = storage.getLayoutVersion();
+          BufferedInputStream bin = new BufferedInputStream(backupInputStream);
+          DataInputStream in = new DataInputStream(bin);
+          Checksum checksum = null;
+          if (logVersion <= -28) { // support fsedits checksum
+            checksum = FSEditLog.getChecksum();
+            in = new DataInputStream(new CheckedInputStream(bin, checksum));
+          }
+          logLoader.loadEditRecords(logVersion, in, checksum, true);
           getFSNamesystem().dir.updateCountForINodeWithQuota(); // inefficient!
           break;
         case INPROGRESS:
@@ -346,14 +356,21 @@ public class BackupImage extends FSImage
     if(jSpoolFile.exists()) {
       // load edits.new
       EditLogFileInputStream edits = new EditLogFileInputStream(jSpoolFile);
-      DataInputStream in = edits.getDataInputStream();
+      BufferedInputStream bin = new BufferedInputStream(edits);
+      DataInputStream in = new DataInputStream(bin);
       FSEditLogLoader logLoader = new FSEditLogLoader(namesystem);
-      numEdits += logLoader.loadFSEdits(in, false);
+      int logVersion = logLoader.readLogVersion(in);
+      Checksum checksum = null;
+      if (logVersion <= -28) { // support fsedits checksum
+        checksum = FSEditLog.getChecksum();
+        in = new DataInputStream(new CheckedInputStream(bin, checksum));
+      }
+      numEdits += logLoader.loadEditRecords(logVersion, in, checksum, false);
 
       // first time reached the end of spool
       jsState = JSpoolState.WAIT;
-      numEdits += logLoader.loadEditRecords(storage.getLayoutVersion(),
-                                            in, true);
+      numEdits += logLoader.loadEditRecords(logVersion,
+                                            in, checksum, true);
       getFSNamesystem().dir.updateCountForINodeWithQuota();
       edits.close();
     }

Modified: hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/EditLogFileOutputStream.java
URL: http://svn.apache.org/viewvc/hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/EditLogFileOutputStream.java?rev=1091131&r1=1091130&r2=1091131&view=diff
==============================================================================
--- hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/EditLogFileOutputStream.java (original)
+++ hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/EditLogFileOutputStream.java Mon Apr 11 17:15:27 2011
@@ -24,6 +24,7 @@ import java.io.IOException;
 import java.io.RandomAccessFile;
 import java.nio.ByteBuffer;
 import java.nio.channels.FileChannel;
+import java.util.zip.Checksum;
 
 import org.apache.hadoop.hdfs.protocol.FSConstants;
 import org.apache.hadoop.io.DataOutputBuffer;
@@ -84,10 +85,18 @@ class EditLogFileOutputStream extends Ed
   /** {@inheritDoc} */
   @Override
   void write(byte op, Writable... writables) throws IOException {
+    int start = bufCurrent.getLength();
     write(op);
     for (Writable w : writables) {
       w.write(bufCurrent);
     }
+    // write transaction checksum
+    int end = bufCurrent.getLength();
+    Checksum checksum = FSEditLog.getChecksum();
+    checksum.reset();
+    checksum.update(bufCurrent.getData(), start, end-start);
+    int sum = (int)checksum.getValue();
+    bufCurrent.writeInt(sum);
   }
 
   /**

Modified: hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/FSEditLog.java
URL: http://svn.apache.org/viewvc/hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/FSEditLog.java?rev=1091131&r1=1091130&r2=1091131&view=diff
==============================================================================
--- hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/FSEditLog.java (original)
+++ hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/FSEditLog.java Mon Apr 11 17:15:27 2011
@@ -22,6 +22,7 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import java.util.zip.Checksum;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -47,6 +48,7 @@ import org.apache.hadoop.io.BytesWritabl
 import org.apache.hadoop.io.LongWritable;
 import org.apache.hadoop.io.Writable;
 import org.apache.hadoop.security.token.delegation.DelegationKey;
+import org.apache.hadoop.util.PureJavaCrc32;
 
 import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.*;
 
@@ -90,6 +92,18 @@ public class FSEditLog implements NNStor
 
   private NNStorage storage;
 
+  private static ThreadLocal<Checksum> localChecksum =
+    new ThreadLocal<Checksum>() {
+    protected Checksum initialValue() {
+      return new PureJavaCrc32();
+    }
+  };
+
+  /** Get a thread local checksum */
+  public static Checksum getChecksum() {
+    return localChecksum.get();
+  }
+
   private static class TransactionId {
     public long txid;
 

Modified: hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/FSEditLogLoader.java
URL: http://svn.apache.org/viewvc/hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/FSEditLogLoader.java?rev=1091131&r1=1091130&r2=1091131&view=diff
==============================================================================
--- hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/FSEditLogLoader.java (original)
+++ hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/FSEditLogLoader.java Mon Apr 11 17:15:27 2011
@@ -17,12 +17,16 @@
  */
 package org.apache.hadoop.hdfs.server.namenode;
 
+import java.io.BufferedInputStream;
 import java.io.DataInput;
 import java.io.DataInputStream;
 import java.io.DataOutput;
 import java.io.EOFException;
 import java.io.IOException;
+import java.util.zip.CheckedInputStream;
+import java.util.zip.Checksum;
 
+import org.apache.hadoop.fs.ChecksumException;
 import org.apache.hadoop.fs.Options.Rename;
 import org.apache.hadoop.fs.permission.FsPermission;
 import org.apache.hadoop.fs.permission.PermissionStatus;
@@ -54,42 +58,62 @@ public class FSEditLogLoader {
    * along.
    */
   int loadFSEdits(EditLogInputStream edits) throws IOException {
-    DataInputStream in = edits.getDataInputStream();
     long startTime = now();
-    int numEdits = loadFSEdits(in, true);
+    int numEdits = loadFSEdits(edits, true);
     FSImage.LOG.info("Edits file " + edits.getName() 
         + " of size " + edits.length() + " edits # " + numEdits 
         + " loaded in " + (now()-startTime)/1000 + " seconds.");
     return numEdits;
   }
 
-  int loadFSEdits(DataInputStream in, boolean closeOnExit) throws IOException {
+  /**
+   * Read the header of fsedit log
+   * @param in fsedit stream
+   * @return the edit log version number
+   * @throws IOException if error occurs
+   */
+  int readLogVersion(DataInputStream in) throws IOException {
+    int logVersion = 0;
+    // Read log file version. Could be missing. 
+    in.mark(4);
+    // If edits log is greater than 2G, available method will return negative
+    // numbers, so we avoid having to call available
+    boolean available = true;
+    try {
+      logVersion = in.readByte();
+    } catch (EOFException e) {
+      available = false;
+    }
+    if (available) {
+      in.reset();
+      logVersion = in.readInt();
+      if (logVersion < FSConstants.LAYOUT_VERSION) // future version
+        throw new IOException(
+            "Unexpected version of the file system log file: "
+            + logVersion + ". Current version = " 
+            + FSConstants.LAYOUT_VERSION + ".");
+    }
+    assert logVersion <= Storage.LAST_UPGRADABLE_LAYOUT_VERSION :
+      "Unsupported version " + logVersion;
+    return logVersion;
+  }
+  
+  int loadFSEdits(EditLogInputStream edits, boolean closeOnExit) throws IOException {
+    BufferedInputStream bin = new BufferedInputStream(edits);
+    DataInputStream in = new DataInputStream(bin);
+    
     int numEdits = 0;
     int logVersion = 0;
 
     try {
-      // Read log file version. Could be missing. 
-      in.mark(4);
-      // If edits log is greater than 2G, available method will return negative
-      // numbers, so we avoid having to call available
-      boolean available = true;
-      try {
-        logVersion = in.readByte();
-      } catch (EOFException e) {
-        available = false;
-      }
-      if (available) {
-        in.reset();
-        logVersion = in.readInt();
-        if (logVersion < FSConstants.LAYOUT_VERSION) // future version
-          throw new IOException(
-                          "Unexpected version of the file system log file: "
-                          + logVersion + ". Current version = " 
-                          + FSConstants.LAYOUT_VERSION + ".");
+      logVersion = readLogVersion(in);
+      Checksum checksum = null;
+      if (logVersion <= -28) { // support fsedits checksum
+        checksum = FSEditLog.getChecksum();
+        in = new DataInputStream(new CheckedInputStream(bin, checksum));
       }
-      assert logVersion <= Storage.LAST_UPGRADABLE_LAYOUT_VERSION :
-                            "Unsupported version " + logVersion;
-      numEdits = loadEditRecords(logVersion, in, false);
+
+      numEdits = loadEditRecords(logVersion, in, checksum, false);
     } finally {
       if(closeOnExit)
         in.close();
@@ -101,7 +125,7 @@ public class FSEditLogLoader {
 
   @SuppressWarnings("deprecation")
   int loadEditRecords(int logVersion, DataInputStream in,
-      boolean closeOnExit) throws IOException {
+      Checksum checksum, boolean closeOnExit) throws IOException {
     FSDirectory fsDir = fsNamesys.dir;
     int numEdits = 0;
     String clientName = null;
@@ -123,6 +147,9 @@ public class FSEditLogLoader {
         long blockSize = 0;
         FSEditLogOpCodes opCode;
         try {
+          if (checksum != null) {
+            checksum.reset();
+          }
           in.mark(1);
           byte opCodeByte = in.readByte();
           opCode = FSEditLogOpCodes.fromByte(opCodeByte);
@@ -480,6 +507,7 @@ public class FSEditLogLoader {
           throw new IOException("Never seen opCode " + opCode);
         }
         }
+        validateChecksum(in, checksum, numEdits);
       }
     } finally {
       if(closeOnExit)
@@ -505,6 +533,22 @@ public class FSEditLogLoader {
     return numEdits;
   }
 
+  /**
+   * Validate a transaction's checksum
+   */
+  private static void validateChecksum(
+      DataInputStream in, Checksum checksum, int tid)
+  throws IOException {
+    if (checksum != null) {
+      int calculatedChecksum = (int)checksum.getValue();
+      int readChecksum = in.readInt(); // read in checksum
+      if (readChecksum != calculatedChecksum) {
+        throw new ChecksumException(
+            "Transaction " + tid + " is corrupt. Calculated checksum is " +
+            calculatedChecksum + " but read checksum " + readChecksum, tid);
+      }
+    }
+  }
 
   /**
    * A class to read in blocks stored in the old format. The only two

Modified: hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/tools/offlineEditsViewer/EditsElement.java
URL: http://svn.apache.org/viewvc/hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/tools/offlineEditsViewer/EditsElement.java?rev=1091131&r1=1091130&r2=1091131&view=diff
==============================================================================
--- hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/tools/offlineEditsViewer/EditsElement.java (original)
+++ hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/tools/offlineEditsViewer/EditsElement.java Mon Apr 11 17:15:27 2011
@@ -80,5 +80,6 @@ public enum EditsElement {
     KEY_ID,
     KEY_EXPIRY_DATE,
     KEY_LENGTH,
-    KEY_BLOB
+    KEY_BLOB,
+    CHECKSUM
 }

Modified: hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/tools/offlineEditsViewer/EditsLoaderCurrent.java
URL: http://svn.apache.org/viewvc/hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/tools/offlineEditsViewer/EditsLoaderCurrent.java?rev=1091131&r1=1091130&r2=1091131&view=diff
==============================================================================
--- hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/tools/offlineEditsViewer/EditsLoaderCurrent.java (original)
+++ hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/tools/offlineEditsViewer/EditsLoaderCurrent.java Mon Apr 11 17:15:27 2011
@@ -17,26 +17,15 @@
  */
 package org.apache.hadoop.hdfs.tools.offlineEditsViewer;
 
-import java.io.DataInputStream;
 import java.io.IOException;
-import java.io.EOFException;
-
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes;
 
 import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.ByteToken;
-import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.ShortToken;
 import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.IntToken;
 import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.VIntToken;
-import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.LongToken;
-import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.VLongToken;
-import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.StringUTF8Token;
-import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.StringTextToken;
-import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.BlobToken;
-import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.BytesWritableToken;
-import static org.apache.hadoop.hdfs.tools.offlineEditsViewer.Tokenizer.EmptyToken;
 
 /**
  * EditsLoaderCurrent processes Hadoop EditLogs files and walks over
@@ -49,7 +38,7 @@ import static org.apache.hadoop.hdfs.too
 class EditsLoaderCurrent implements EditsLoader {
 
   private static int [] supportedVersions = {
-    -18, -19, -20, -21, -22, -23, -24, -25, -26, -27 };
+    -18, -19, -20, -21, -22, -23, -24, -25, -26, -27, -28 };
 
   private EditsVisitor v;
   private int editsVersion = 0;
@@ -464,6 +453,10 @@ class EditsLoaderCurrent implements Edit
         visitOpCode(editsOpCode);
 
         v.leaveEnclosingElement(); // DATA
+        
+        if (editsOpCode != FSEditLogOpCodes.OP_INVALID && editsVersion <= -28) {
+          v.visitInt(EditsElement.CHECKSUM);
+        }
         v.leaveEnclosingElement(); // RECORD
       } while(editsOpCode != FSEditLogOpCodes.OP_INVALID);
 

Modified: hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/tools/offlineImageViewer/ImageLoaderCurrent.java
URL: http://svn.apache.org/viewvc/hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/tools/offlineImageViewer/ImageLoaderCurrent.java?rev=1091131&r1=1091130&r2=1091131&view=diff
==============================================================================
--- hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/tools/offlineImageViewer/ImageLoaderCurrent.java (original)
+++ hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/tools/offlineImageViewer/ImageLoaderCurrent.java Mon Apr 11 17:15:27 2011
@@ -121,7 +121,7 @@ class ImageLoaderCurrent implements Imag
   protected final DateFormat dateFormat = 
                                       new SimpleDateFormat("yyyy-MM-dd HH:mm");
   private static int [] versions = 
-    {-16, -17, -18, -19, -20, -21, -22, -23, -24, -25, -26, -27};
+    {-16, -17, -18, -19, -20, -21, -22, -23, -24, -25, -26, -27, -28};
   private int imageVersion = 0;
 
   /* (non-Javadoc)

Modified: hadoop/hdfs/trunk/src/test/hdfs/org/apache/hadoop/hdfs/server/namenode/TestEditLog.java
URL: http://svn.apache.org/viewvc/hadoop/hdfs/trunk/src/test/hdfs/org/apache/hadoop/hdfs/server/namenode/TestEditLog.java?rev=1091131&r1=1091130&r2=1091131&view=diff
==============================================================================
--- hadoop/hdfs/trunk/src/test/hdfs/org/apache/hadoop/hdfs/server/namenode/TestEditLog.java (original)
+++ hadoop/hdfs/trunk/src/test/hdfs/org/apache/hadoop/hdfs/server/namenode/TestEditLog.java Mon Apr 11 17:15:27 2011
@@ -20,12 +20,15 @@ package org.apache.hadoop.hdfs.server.na
 import junit.framework.TestCase;
 import java.io.*;
 import java.net.URI;
+import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.ChecksumException;
 import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.fs.permission.*;
 
 import org.apache.hadoop.hdfs.HdfsConfiguration;
@@ -303,4 +306,37 @@ public class TestEditLog extends TestCas
       if(cluster != null) cluster.shutdown();
     }
   }
+  
+  public void testEditChecksum() throws Exception {
+    // start a cluster 
+    Configuration conf = new HdfsConfiguration();
+    MiniDFSCluster cluster = null;
+    FileSystem fileSys = null;
+    cluster = new MiniDFSCluster.Builder(conf).numDataNodes(NUM_DATA_NODES).build();
+    cluster.waitActive();
+    fileSys = cluster.getFileSystem();
+    final FSNamesystem namesystem = cluster.getNamesystem();
+
+    FSImage fsimage = namesystem.getFSImage();
+    final FSEditLog editLog = fsimage.getEditLog();
+    fileSys.mkdirs(new Path("/tmp"));
+    File editFile = editLog.getFsEditName();
+    editLog.close();
+    cluster.shutdown();
+      long fileLen = editFile.length();
+    System.out.println("File name: " + editFile + " len: " + fileLen);
+    RandomAccessFile rwf = new RandomAccessFile(editFile, "rw");
+    rwf.seek(fileLen-4); // seek to checksum bytes
+    int b = rwf.readInt();
+    rwf.seek(fileLen-4);
+    rwf.writeInt(b+1);
+    rwf.close();
+    
+    try {
+      cluster = new MiniDFSCluster.Builder(conf).numDataNodes(NUM_DATA_NODES).format(false).build();
+      fail("should not be able to start");
+    } catch (ChecksumException e) {
+      // expected
+    }
+  }
 }