commit 97893a0af9748da1bee95ec3fabe89ac77ac9ada

Author: Konstantin Shvachko <shv@cdev6023.inktomisearch.com>
Date:   Wed Jul 21 02:35:52 2010 +0000

    HDFS:1161 from https://issues.apache.org/jira/secure/attachment/12450011/HDFS-1161-y20.patch
    
    +++ b/YAHOO-CHANGES.txt
    +    HDFS-1161. Make DN minimum valid volumes configurable. (shv)
    +


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.20-security-patches@1077572 13f79535-47bb-0310-9956-ffa450edef68

src/hdfs/hdfs-default.xml

@@ -417,4 +417,13 @@ creations/deletions), or "all".</description>
   </description>
 </property>
 
+<property>
+  <name>dfs.datanode.failed.volumes.tolerated</name>
+  <value>0</value>
+  <description>The number of volumes that are allowed to
+  fail before a datanode stops offering service. By default
+  any volume failure will cause a datanode to shutdown.
+  </description>
+</property>
+
 </configuration>

src/hdfs/org/apache/hadoop/hdfs/protocol/FSConstants.java

@@ -56,7 +56,6 @@ public interface FSConstants {
   public static final int DEFAULT_DATA_SOCKET_SIZE = 128 * 1024;
 
   public static final int SIZE_OF_INTEGER = Integer.SIZE / Byte.SIZE;
-  public static final int MIN_NUM_OF_VALID_VOLUMES = 1;// for a DN to run
 
   // SafeMode actions
   public enum SafeModeAction{ SAFEMODE_LEAVE, SAFEMODE_ENTER, SAFEMODE_GET; }

src/hdfs/org/apache/hadoop/hdfs/server/datanode/FSDataset.java

@@ -746,12 +746,24 @@ public class FSDataset implements FSConstants, FSDatasetInterface {
   private int maxBlocksPerDir = 0;
   private HashMap<Block,DatanodeBlockInfo> volumeMap = null;
   static  Random random = new Random();
+  private int validVolsRequired;
   
   /**
    * An FSDataset has a directory where it loads its data files.
    */
   public FSDataset(DataStorage storage, Configuration conf) throws IOException {
     this.maxBlocksPerDir = conf.getInt("dfs.datanode.numblocks", 64);
+    // 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 =
+      conf.getInt("dfs.datanode.failed.volumes.tolerated",
+                  0);
+    this.validVolsRequired = storage.getNumStorageDirs() - volFailuresTolerated; 
+    if (validVolsRequired < 1 ||
+        validVolsRequired > storage.getNumStorageDirs()) {
+      DataNode.LOG.error("Invalid value " + volFailuresTolerated + " for " +
+          "dfs.datanode.failed.volumes.tolerated");
+    }
     FSVolume[] volArray = new FSVolume[storage.getNumStorageDirs()];
     for (int idx = 0; idx < storage.getNumStorageDirs(); idx++) {
       volArray[idx] = new FSVolume(storage.getStorageDir(idx).getCurrentDir(), conf);
@@ -768,12 +780,12 @@ public class FSDataset implements FSConstants, FSDatasetInterface {
   public long getDfsUsed() throws IOException {
     return volumes.getDfsUsed();
   }
+
   /**
-   * Return true - if there are still valid volumes 
-   * on the DataNode
+   * Return true - if there are still valid volumes on the DataNode. 
    */
-  public boolean hasEnoughResource(){
-    return volumes.numberOfVolumes() >= MIN_NUM_OF_VALID_VOLUMES;
+  public boolean hasEnoughResource() {
+    return volumes.numberOfVolumes() >= validVolsRequired; 
   }
 
   /**

src/test/org/apache/hadoop/hdfs/server/datanode/TestDataNodeVolumeFailure.java

@@ -0,0 +1,369 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hdfs.server.datanode;
+
+import java.io.File;
+import java.io.FilenameFilter;
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.net.Socket;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import junit.framework.TestCase;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.FileUtil;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.hdfs.DFSClient;
+import org.apache.hadoop.hdfs.DFSTestUtil;
+import org.apache.hadoop.hdfs.MiniDFSCluster;
+import org.apache.hadoop.hdfs.protocol.Block;
+import org.apache.hadoop.hdfs.protocol.BlockListAsLongs;
+import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
+import org.apache.hadoop.hdfs.protocol.LocatedBlock;
+import org.apache.hadoop.hdfs.server.common.HdfsConstants;
+import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
+import org.apache.hadoop.hdfs.server.namenode.NameNode;
+import org.apache.hadoop.net.NetUtils;
+//import org.junit.After;
+//import org.junit.Before;
+
+public class TestDataNodeVolumeFailure extends TestCase{
+  final private int block_size = 512;
+  MiniDFSCluster cluster = null;
+  int dn_num = 2;
+  int blocks_num = 30;
+  short repl=2;
+  File dataDir = null;
+  File data_fail = null;
+  File failedDir = null;
+  
+  // mapping blocks to Meta files(physical files) and locs(NameNode locations)
+  private class BlockLocs {
+    public int num_files = 0;
+    public int num_locs = 0;
+  }
+  // block id to BlockLocs
+  Map<String, BlockLocs> block_map = new HashMap<String, BlockLocs> ();
+
+  //@Before
+  public void setUp() throws Exception {
+    
+    // bring up a cluster of 2
+    Configuration conf = new Configuration();
+    conf.setLong("dfs.block.size", block_size);
+    // Allow a single volume failure (there are two volumes)
+    conf.setInt("dfs.datanode.failed.volumes.tolerated", 1);
+    cluster = new MiniDFSCluster(conf, dn_num, true, null);
+    cluster.waitActive();
+  }
+  
+  
+  
+  public void testVolumeFailure() throws IOException {
+    FileSystem fs = cluster.getFileSystem();
+    dataDir = new File(cluster.getDataDirectory());
+    System.out.println("Data dir: is " +  dataDir.getPath());
+   
+    
+    // Data dir structure is dataDir/data[1-4]/[current,tmp...]
+    // data1,2 is for datanode 1, data2,3 - datanode2 
+    String filename = "/test.txt";
+    Path filePath = new Path(filename);
+    
+    // we use only small number of blocks to avoid creating subdirs in the data dir..
+    int filesize = block_size*blocks_num;
+    DFSTestUtil.createFile(fs, filePath, filesize, repl, 1L);
+    DFSTestUtil.waitReplication(fs, filePath, repl);
+    System.out.println("file " + filename + "(size " +
+        filesize + ") is created and replicated");
+   
+    // fail the volume
+    // delete/make non-writable one of the directories (failed volume)
+    data_fail = new File(dataDir, "data3");
+    failedDir = new File(data_fail, "current");
+    if (failedDir.exists() &&
+        //!FileUtil.fullyDelete(failedDir)
+        !deteteBlocks(failedDir)
+        ) {
+      throw new IOException("Could not delete hdfs directory '" + failedDir + "'");
+    }    
+    data_fail.setReadOnly();
+    failedDir.setReadOnly();
+    System.out.println("Deleteing " + failedDir.getPath() + "; exist=" + failedDir.exists());
+    
+    // access all the blocks on the "failed" DataNode, 
+    // we need to make sure that the "failed" volume is being accessed - 
+    // and that will cause failure, blocks removal, "emergency" block report
+    triggerFailure(filename, filesize);
+    
+    // make sure a block report is sent 
+    DataNode dn = cluster.getDataNodes().get(1); //corresponds to dir data3
+    cluster.getNameNode().blockReport(dn.dnRegistration,
+        BlockListAsLongs.convertToArrayLongs(cluster.getBlockReport(1)));
+
+    // verify number of blocks and files...
+    verify(filename, filesize);
+    
+    // create another file (with one volume failed).
+    System.out.println("creating file test1.txt");
+    Path fileName1 = new Path("/test1.txt");
+    DFSTestUtil.createFile(fs, fileName1, filesize, repl, 1L);
+    
+    
+    // should be able to replicate to both nodes (2 DN, repl=2)
+    DFSTestUtil.waitReplication(fs, fileName1, repl);
+    System.out.println("file " + fileName1.getName() + 
+        " is created and replicated");
+    
+  }
+  
+  /**
+   * verifies two things:
+   *  1. number of locations of each block in the name node
+   *   matches number of actual files
+   *  2. block files + pending block equals to total number of blocks that a file has 
+   *     including the replication (HDFS file has 30 blocks, repl=2 - total 60
+   * @param fn - file name
+   * @param fs - file size
+   * @throws IOException
+   */
+  private void verify(String fn, int fs) throws IOException{
+    // now count how many physical blocks are there
+    int totalReal = countRealBlocks(block_map);
+    System.out.println("countRealBlocks counted " + totalReal + " blocks");
+
+    // count how many blocks store in NN structures.
+    int totalNN = countNNBlocks(block_map, fn, fs);
+    System.out.println("countNNBlocks counted " + totalNN + " blocks");
+
+    for(String bid : block_map.keySet()) {
+      BlockLocs bl = block_map.get(bid);
+      // System.out.println(bid + "->" + bl.num_files + "vs." + bl.num_locs);
+      // number of physical files (1 or 2) should be same as number of datanodes
+      // in the list of the block locations
+      assertEquals(bl.num_files, bl.num_locs);
+    }
+    // verify we have the same number of physical blocks and stored in NN
+    assertEquals(totalReal, totalNN);
+
+    // now check the number of under-replicated blocks
+    FSNamesystem fsn = FSNamesystem.getFSNamesystem();
+    // force update of all the metric counts by calling computeDatanodeWork
+    fsn.computeDatanodeWork();
+    // get all the counts 
+    long underRepl = fsn.getUnderReplicatedBlocks();
+    long pendRepl = fsn.getPendingReplicationBlocks();
+    long totalRepl = underRepl + pendRepl;
+    System.out.println("underreplicated after = "+ underRepl + 
+        " and pending repl ="  + pendRepl + "; total underRepl = " + totalRepl);
+
+    System.out.println("total blocks (real and replicating):" + 
+        (totalReal + totalRepl) + " vs. all files blocks " + blocks_num*2);
+
+    // together all the blocks should be equal to all real + all underreplicated
+    assertEquals(totalReal + totalRepl, blocks_num*repl);
+  }
+  
+  /**
+   * go to each block on the 2nd DataNode until it fails...
+   * @param path
+   * @param size
+   * @throws IOException
+   */
+  private void triggerFailure(String path, long size) throws IOException {
+    NameNode nn = cluster.getNameNode();
+    List<LocatedBlock> locatedBlocks = nn.getBlockLocations(path, 0, size).getLocatedBlocks();
+//    System.out.println("Number of blocks: " + locatedBlocks.size()); 
+    
+    for(LocatedBlock lb : locatedBlocks) {
+      DatanodeInfo dinfo = lb.getLocations()[1];
+      Block b = lb.getBlock();
+    //  System.out.println(i++ + ". " + b.getBlockName());
+      try {
+        accessBlock(dinfo, lb);
+      } catch (IOException e) {
+        System.out.println("Failure triggered, on block: " + b.getBlockId() +  
+            "; corresponding volume should be removed by now");
+        break;
+      }
+    }
+  }
+  
+  /**
+   * simulate failure delete all the block files
+   * @param dir
+   * @throws IOException
+   */
+  private boolean deteteBlocks(File dir) {
+    
+    File [] fileList = dir.listFiles();
+    for(File f : fileList) {
+      if(f.getName().startsWith("blk_")) {
+        if(!f.delete())
+          return false;
+        
+      }
+    }
+    
+    return true;
+  }
+  
+  /**
+   * try to access a block on a data node. If fails - throws exception
+   * @param datanode
+   * @param lblock
+   * @throws IOException
+   */
+  private void accessBlock(DatanodeInfo datanode, LocatedBlock lblock)
+    throws IOException {
+    InetSocketAddress targetAddr = null;
+    Socket s = null;
+    DFSClient.BlockReader blockReader = null; 
+    Block block = lblock.getBlock(); 
+   
+    targetAddr = NetUtils.createSocketAddr(datanode.getName());
+      
+    s = new Socket();
+    s.connect(targetAddr, HdfsConstants.READ_TIMEOUT);
+    s.setSoTimeout(HdfsConstants.READ_TIMEOUT);
+
+    blockReader = 
+      DFSClient.BlockReader.newBlockReader(s, targetAddr.toString() + ":" + 
+          block.getBlockId(), 
+          block.getBlockId(), 
+          block.getGenerationStamp(), 
+          0, -1, 4096);
+
+    // nothing - if it fails - it will throw and exception
+  }
+  
+  /**
+   * Count datanodes that have copies of the blocks for a file
+   * put it into the map
+   * @param map
+   * @param path
+   * @param size
+   * @return
+   * @throws IOException
+   */
+  private int countNNBlocks(Map<String, BlockLocs> map, String path, long size) 
+    throws IOException {
+    int total = 0;
+    
+    NameNode nn = cluster.getNameNode();
+    List<LocatedBlock> locatedBlocks = 
+      nn.getBlockLocations(path, 0, size).getLocatedBlocks();
+    //System.out.println("Number of blocks: " + locatedBlocks.size()); 
+        
+    for(LocatedBlock lb : locatedBlocks) {
+      String blockId = ""+lb.getBlock().getBlockId();
+      //System.out.print(blockId + ": ");
+      DatanodeInfo[] dn_locs = lb.getLocations();
+      BlockLocs bl = map.get(blockId);
+      if(bl == null) {
+        bl = new BlockLocs();
+      }
+      //System.out.print(dn_info.name+",");
+      total += dn_locs.length;        
+      bl.num_locs += dn_locs.length;
+      map.put(blockId, bl);
+      //System.out.println();
+    }
+    return total;
+  }
+  
+  /**
+   *  look for real blocks
+   *  by counting *.meta files in all the storage dirs 
+   * @param map
+   * @return
+   */
+
+  private int countRealBlocks(Map<String, BlockLocs> map) {
+    int total = 0;
+    for(int i=0; i<dn_num; i++) {
+      for(int j=1; j<=2; j++) {
+        File dir = new File(new File(dataDir, "data"+(2*i+j)), "current");
+        if(dir == null) {
+          System.out.println("dir is null for dn=" + i + " and data_dir=" + j);
+          continue;
+        }
+      
+        String [] res = metaFilesInDir(dir);
+        if(res == null) {
+          System.out.println("res is null for dir = " + dir + " i=" + i + " and j=" + j);
+          continue;
+        }
+        //System.out.println("for dn" + i + "." + j + ": " + dir + "=" + res.length+ " files");
+      
+        //int ii = 0;
+        for(String s: res) {
+          // cut off "blk_-" at the beginning and ".meta" at the end
+          assertNotNull(s);
+          String bid = s.substring(s.indexOf("_")+1, s.lastIndexOf("_"));
+          //System.out.println(ii++ + ". block " + s + "; id=" + bid);
+          BlockLocs val = map.get(bid);
+          if(val == null) {
+            val = new BlockLocs();
+          }
+          val.num_files ++; // one more file for the block
+          map.put(bid, val);
+
+        }
+        //System.out.println("dir1="+dir.getPath() + "blocks=" + res.length);
+        //System.out.println("dir2="+dir2.getPath() + "blocks=" + res2.length);
+
+        total += res.length;
+      }
+    }
+    return total;
+  }
+
+  /*
+   * count how many files *.meta are in the dir
+   */
+  private String [] metaFilesInDir(File dir) {
+    String [] res = dir.list(
+        new FilenameFilter() {
+          public boolean accept(File dir, String name) {
+            return name.startsWith("blk_") &&
+            name.endsWith(FSDataset.METADATA_EXTENSION);
+          }
+        }
+    );
+    return res;
+  }
+
+  //@After
+  public void tearDown() throws Exception {
+    if(data_fail != null) {
+      data_fail.setWritable(true);
+    }
+    if(failedDir != null) {
+      failedDir.setWritable(true);
+    }
+    if(cluster != null) {
+      cluster.shutdown();
+    }
+  }
+
+}