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From a...@apache.org
Subject [31/41] hbase git commit: HBASE-18640 Move mapreduce out of hbase-server into separate module.
Date Sat, 26 Aug 2017 01:39:31 GMT
http://git-wip-us.apache.org/repos/asf/hbase/blob/664b6be0/hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/snapshot/ExportSnapshot.java
----------------------------------------------------------------------
diff --git a/hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/snapshot/ExportSnapshot.java b/hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/snapshot/ExportSnapshot.java
new file mode 100644
index 0000000..e80410f
--- /dev/null
+++ b/hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/snapshot/ExportSnapshot.java
@@ -0,0 +1,1111 @@
+/**
+ * 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.hbase.snapshot;
+
+import java.io.BufferedInputStream;
+import java.io.FileNotFoundException;
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.LinkedList;
+import java.util.List;
+
+import org.apache.commons.cli.CommandLine;
+import org.apache.commons.cli.Option;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FSDataInputStream;
+import org.apache.hadoop.fs.FSDataOutputStream;
+import org.apache.hadoop.fs.FileChecksum;
+import org.apache.hadoop.fs.FileStatus;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.FileUtil;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.fs.permission.FsPermission;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.HBaseConfiguration;
+import org.apache.hadoop.hbase.HConstants;
+import org.apache.hadoop.hbase.HRegionInfo;
+import org.apache.hadoop.hbase.io.FileLink;
+import org.apache.hadoop.hbase.io.HFileLink;
+import org.apache.hadoop.hbase.io.WALLink;
+import org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;
+import org.apache.hadoop.hbase.mob.MobUtils;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.SnapshotProtos.SnapshotDescription;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.SnapshotProtos.SnapshotFileInfo;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.SnapshotProtos.SnapshotRegionManifest;
+import org.apache.hadoop.hbase.util.AbstractHBaseTool;
+import org.apache.hadoop.hbase.util.FSUtils;
+import org.apache.hadoop.hbase.util.HFileArchiveUtil;
+import org.apache.hadoop.hbase.util.Pair;
+import org.apache.hadoop.io.BytesWritable;
+import org.apache.hadoop.io.IOUtils;
+import org.apache.hadoop.io.NullWritable;
+import org.apache.hadoop.io.Writable;
+import org.apache.hadoop.mapreduce.Job;
+import org.apache.hadoop.mapreduce.JobContext;
+import org.apache.hadoop.mapreduce.Mapper;
+import org.apache.hadoop.mapreduce.InputFormat;
+import org.apache.hadoop.mapreduce.InputSplit;
+import org.apache.hadoop.mapreduce.RecordReader;
+import org.apache.hadoop.mapreduce.TaskAttemptContext;
+import org.apache.hadoop.mapreduce.lib.output.NullOutputFormat;
+import org.apache.hadoop.mapreduce.security.TokenCache;
+import org.apache.hadoop.hbase.io.hadoopbackport.ThrottledInputStream;
+import org.apache.hadoop.util.StringUtils;
+import org.apache.hadoop.util.Tool;
+
+/**
+ * Export the specified snapshot to a given FileSystem.
+ *
+ * The .snapshot/name folder is copied to the destination cluster
+ * and then all the hfiles/wals are copied using a Map-Reduce Job in the .archive/ location.
+ * When everything is done, the second cluster can restore the snapshot.
+ */
+@InterfaceAudience.Public
+public class ExportSnapshot extends AbstractHBaseTool implements Tool {
+  public static final String NAME = "exportsnapshot";
+  /** Configuration prefix for overrides for the source filesystem */
+  public static final String CONF_SOURCE_PREFIX = NAME + ".from.";
+  /** Configuration prefix for overrides for the destination filesystem */
+  public static final String CONF_DEST_PREFIX = NAME + ".to.";
+
+  private static final Log LOG = LogFactory.getLog(ExportSnapshot.class);
+
+  private static final String MR_NUM_MAPS = "mapreduce.job.maps";
+  private static final String CONF_NUM_SPLITS = "snapshot.export.format.splits";
+  private static final String CONF_SNAPSHOT_NAME = "snapshot.export.format.snapshot.name";
+  private static final String CONF_SNAPSHOT_DIR = "snapshot.export.format.snapshot.dir";
+  private static final String CONF_FILES_USER = "snapshot.export.files.attributes.user";
+  private static final String CONF_FILES_GROUP = "snapshot.export.files.attributes.group";
+  private static final String CONF_FILES_MODE = "snapshot.export.files.attributes.mode";
+  private static final String CONF_CHECKSUM_VERIFY = "snapshot.export.checksum.verify";
+  private static final String CONF_OUTPUT_ROOT = "snapshot.export.output.root";
+  private static final String CONF_INPUT_ROOT = "snapshot.export.input.root";
+  private static final String CONF_BUFFER_SIZE = "snapshot.export.buffer.size";
+  private static final String CONF_MAP_GROUP = "snapshot.export.default.map.group";
+  private static final String CONF_BANDWIDTH_MB = "snapshot.export.map.bandwidth.mb";
+  protected static final String CONF_SKIP_TMP = "snapshot.export.skip.tmp";
+
+  static class Testing {
+    static final String CONF_TEST_FAILURE = "test.snapshot.export.failure";
+    static final String CONF_TEST_FAILURE_COUNT = "test.snapshot.export.failure.count";
+    int failuresCountToInject = 0;
+    int injectedFailureCount = 0;
+  }
+
+  // Command line options and defaults.
+  static final class Options {
+    static final Option SNAPSHOT = new Option(null, "snapshot", true, "Snapshot to restore.");
+    static final Option TARGET_NAME = new Option(null, "target", true,
+        "Target name for the snapshot.");
+    static final Option COPY_TO = new Option(null, "copy-to", true, "Remote "
+        + "destination hdfs://");
+    static final Option COPY_FROM = new Option(null, "copy-from", true,
+        "Input folder hdfs:// (default hbase.rootdir)");
+    static final Option NO_CHECKSUM_VERIFY = new Option(null, "no-checksum-verify", false,
+        "Do not verify checksum, use name+length only.");
+    static final Option NO_TARGET_VERIFY = new Option(null, "no-target-verify", false,
+        "Do not verify the integrity of the exported snapshot.");
+    static final Option OVERWRITE = new Option(null, "overwrite", false,
+        "Rewrite the snapshot manifest if already exists.");
+    static final Option CHUSER = new Option(null, "chuser", true,
+        "Change the owner of the files to the specified one.");
+    static final Option CHGROUP = new Option(null, "chgroup", true,
+        "Change the group of the files to the specified one.");
+    static final Option CHMOD = new Option(null, "chmod", true,
+        "Change the permission of the files to the specified one.");
+    static final Option MAPPERS = new Option(null, "mappers", true,
+        "Number of mappers to use during the copy (mapreduce.job.maps).");
+    static final Option BANDWIDTH = new Option(null, "bandwidth", true,
+        "Limit bandwidth to this value in MB/second.");
+  }
+
+  // Export Map-Reduce Counters, to keep track of the progress
+  public enum Counter {
+    MISSING_FILES, FILES_COPIED, FILES_SKIPPED, COPY_FAILED,
+    BYTES_EXPECTED, BYTES_SKIPPED, BYTES_COPIED
+  }
+
+  private static class ExportMapper extends Mapper<BytesWritable, NullWritable,
+                                                   NullWritable, NullWritable> {
+    private static final Log LOG = LogFactory.getLog(ExportMapper.class);
+    final static int REPORT_SIZE = 1 * 1024 * 1024;
+    final static int BUFFER_SIZE = 64 * 1024;
+
+    private boolean verifyChecksum;
+    private String filesGroup;
+    private String filesUser;
+    private short filesMode;
+    private int bufferSize;
+
+    private FileSystem outputFs;
+    private Path outputArchive;
+    private Path outputRoot;
+
+    private FileSystem inputFs;
+    private Path inputArchive;
+    private Path inputRoot;
+
+    private static Testing testing = new Testing();
+
+    @Override
+    public void setup(Context context) throws IOException {
+      Configuration conf = context.getConfiguration();
+
+      Configuration srcConf = HBaseConfiguration.createClusterConf(conf, null, CONF_SOURCE_PREFIX);
+      Configuration destConf = HBaseConfiguration.createClusterConf(conf, null, CONF_DEST_PREFIX);
+
+      verifyChecksum = conf.getBoolean(CONF_CHECKSUM_VERIFY, true);
+
+      filesGroup = conf.get(CONF_FILES_GROUP);
+      filesUser = conf.get(CONF_FILES_USER);
+      filesMode = (short)conf.getInt(CONF_FILES_MODE, 0);
+      outputRoot = new Path(conf.get(CONF_OUTPUT_ROOT));
+      inputRoot = new Path(conf.get(CONF_INPUT_ROOT));
+
+      inputArchive = new Path(inputRoot, HConstants.HFILE_ARCHIVE_DIRECTORY);
+      outputArchive = new Path(outputRoot, HConstants.HFILE_ARCHIVE_DIRECTORY);
+
+      try {
+        srcConf.setBoolean("fs." + inputRoot.toUri().getScheme() + ".impl.disable.cache", true);
+        inputFs = FileSystem.get(inputRoot.toUri(), srcConf);
+      } catch (IOException e) {
+        throw new IOException("Could not get the input FileSystem with root=" + inputRoot, e);
+      }
+
+      try {
+        destConf.setBoolean("fs." + outputRoot.toUri().getScheme() + ".impl.disable.cache", true);
+        outputFs = FileSystem.get(outputRoot.toUri(), destConf);
+      } catch (IOException e) {
+        throw new IOException("Could not get the output FileSystem with root="+ outputRoot, e);
+      }
+
+      // Use the default block size of the outputFs if bigger
+      int defaultBlockSize = Math.max((int) outputFs.getDefaultBlockSize(outputRoot), BUFFER_SIZE);
+      bufferSize = conf.getInt(CONF_BUFFER_SIZE, defaultBlockSize);
+      LOG.info("Using bufferSize=" + StringUtils.humanReadableInt(bufferSize));
+
+      for (Counter c : Counter.values()) {
+        context.getCounter(c).increment(0);
+      }
+      if (context.getConfiguration().getBoolean(Testing.CONF_TEST_FAILURE, false)) {
+        testing.failuresCountToInject = conf.getInt(Testing.CONF_TEST_FAILURE_COUNT, 0);
+        // Get number of times we have already injected failure based on attempt number of this
+        // task.
+        testing.injectedFailureCount = context.getTaskAttemptID().getId();
+      }
+    }
+
+    @Override
+    protected void cleanup(Context context) {
+      IOUtils.closeStream(inputFs);
+      IOUtils.closeStream(outputFs);
+    }
+
+    @Override
+    public void map(BytesWritable key, NullWritable value, Context context)
+        throws InterruptedException, IOException {
+      SnapshotFileInfo inputInfo = SnapshotFileInfo.parseFrom(key.copyBytes());
+      Path outputPath = getOutputPath(inputInfo);
+
+      copyFile(context, inputInfo, outputPath);
+    }
+
+    /**
+     * Returns the location where the inputPath will be copied.
+     */
+    private Path getOutputPath(final SnapshotFileInfo inputInfo) throws IOException {
+      Path path = null;
+      switch (inputInfo.getType()) {
+        case HFILE:
+          Path inputPath = new Path(inputInfo.getHfile());
+          String family = inputPath.getParent().getName();
+          TableName table =HFileLink.getReferencedTableName(inputPath.getName());
+          String region = HFileLink.getReferencedRegionName(inputPath.getName());
+          String hfile = HFileLink.getReferencedHFileName(inputPath.getName());
+          path = new Path(FSUtils.getTableDir(new Path("./"), table),
+              new Path(region, new Path(family, hfile)));
+          break;
+        case WAL:
+          LOG.warn("snapshot does not keeps WALs: " + inputInfo);
+          break;
+        default:
+          throw new IOException("Invalid File Type: " + inputInfo.getType().toString());
+      }
+      return new Path(outputArchive, path);
+    }
+
+    /**
+     * Used by TestExportSnapshot to test for retries when failures happen.
+     * Failure is injected in {@link #copyFile(Context, SnapshotFileInfo, Path)}.
+     */
+    private void injectTestFailure(final Context context, final SnapshotFileInfo inputInfo)
+        throws IOException {
+      if (!context.getConfiguration().getBoolean(Testing.CONF_TEST_FAILURE, false)) return;
+      if (testing.injectedFailureCount >= testing.failuresCountToInject) return;
+      testing.injectedFailureCount++;
+      context.getCounter(Counter.COPY_FAILED).increment(1);
+      LOG.debug("Injecting failure. Count: " + testing.injectedFailureCount);
+      throw new IOException(String.format("TEST FAILURE (%d of max %d): Unable to copy input=%s",
+          testing.injectedFailureCount, testing.failuresCountToInject, inputInfo));
+    }
+
+    private void copyFile(final Context context, final SnapshotFileInfo inputInfo,
+        final Path outputPath) throws IOException {
+      // Get the file information
+      FileStatus inputStat = getSourceFileStatus(context, inputInfo);
+
+      // Verify if the output file exists and is the same that we want to copy
+      if (outputFs.exists(outputPath)) {
+        FileStatus outputStat = outputFs.getFileStatus(outputPath);
+        if (outputStat != null && sameFile(inputStat, outputStat)) {
+          LOG.info("Skip copy " + inputStat.getPath() + " to " + outputPath + ", same file.");
+          context.getCounter(Counter.FILES_SKIPPED).increment(1);
+          context.getCounter(Counter.BYTES_SKIPPED).increment(inputStat.getLen());
+          return;
+        }
+      }
+
+      InputStream in = openSourceFile(context, inputInfo);
+      int bandwidthMB = context.getConfiguration().getInt(CONF_BANDWIDTH_MB, 100);
+      if (Integer.MAX_VALUE != bandwidthMB) {
+        in = new ThrottledInputStream(new BufferedInputStream(in), bandwidthMB * 1024 * 1024L);
+      }
+
+      try {
+        context.getCounter(Counter.BYTES_EXPECTED).increment(inputStat.getLen());
+
+        // Ensure that the output folder is there and copy the file
+        createOutputPath(outputPath.getParent());
+        FSDataOutputStream out = outputFs.create(outputPath, true);
+        try {
+          copyData(context, inputStat.getPath(), in, outputPath, out, inputStat.getLen());
+        } finally {
+          out.close();
+        }
+
+        // Try to Preserve attributes
+        if (!preserveAttributes(outputPath, inputStat)) {
+          LOG.warn("You may have to run manually chown on: " + outputPath);
+        }
+      } finally {
+        in.close();
+        injectTestFailure(context, inputInfo);
+      }
+    }
+
+    /**
+     * Create the output folder and optionally set ownership.
+     */
+    private void createOutputPath(final Path path) throws IOException {
+      if (filesUser == null && filesGroup == null) {
+        outputFs.mkdirs(path);
+      } else {
+        Path parent = path.getParent();
+        if (!outputFs.exists(parent) && !parent.isRoot()) {
+          createOutputPath(parent);
+        }
+        outputFs.mkdirs(path);
+        if (filesUser != null || filesGroup != null) {
+          // override the owner when non-null user/group is specified
+          outputFs.setOwner(path, filesUser, filesGroup);
+        }
+        if (filesMode > 0) {
+          outputFs.setPermission(path, new FsPermission(filesMode));
+        }
+      }
+    }
+
+    /**
+     * Try to Preserve the files attribute selected by the user copying them from the source file
+     * This is only required when you are exporting as a different user than "hbase" or on a system
+     * that doesn't have the "hbase" user.
+     *
+     * This is not considered a blocking failure since the user can force a chmod with the user
+     * that knows is available on the system.
+     */
+    private boolean preserveAttributes(final Path path, final FileStatus refStat) {
+      FileStatus stat;
+      try {
+        stat = outputFs.getFileStatus(path);
+      } catch (IOException e) {
+        LOG.warn("Unable to get the status for file=" + path);
+        return false;
+      }
+
+      try {
+        if (filesMode > 0 && stat.getPermission().toShort() != filesMode) {
+          outputFs.setPermission(path, new FsPermission(filesMode));
+        } else if (refStat != null && !stat.getPermission().equals(refStat.getPermission())) {
+          outputFs.setPermission(path, refStat.getPermission());
+        }
+      } catch (IOException e) {
+        LOG.warn("Unable to set the permission for file="+ stat.getPath() +": "+ e.getMessage());
+        return false;
+      }
+
+      boolean hasRefStat = (refStat != null);
+      String user = stringIsNotEmpty(filesUser) || !hasRefStat ? filesUser : refStat.getOwner();
+      String group = stringIsNotEmpty(filesGroup) || !hasRefStat ? filesGroup : refStat.getGroup();
+      if (stringIsNotEmpty(user) || stringIsNotEmpty(group)) {
+        try {
+          if (!(user.equals(stat.getOwner()) && group.equals(stat.getGroup()))) {
+            outputFs.setOwner(path, user, group);
+          }
+        } catch (IOException e) {
+          LOG.warn("Unable to set the owner/group for file="+ stat.getPath() +": "+ e.getMessage());
+          LOG.warn("The user/group may not exist on the destination cluster: user=" +
+                   user + " group=" + group);
+          return false;
+        }
+      }
+
+      return true;
+    }
+
+    private boolean stringIsNotEmpty(final String str) {
+      return str != null && str.length() > 0;
+    }
+
+    private void copyData(final Context context,
+        final Path inputPath, final InputStream in,
+        final Path outputPath, final FSDataOutputStream out,
+        final long inputFileSize)
+        throws IOException {
+      final String statusMessage = "copied %s/" + StringUtils.humanReadableInt(inputFileSize) +
+                                   " (%.1f%%)";
+
+      try {
+        byte[] buffer = new byte[bufferSize];
+        long totalBytesWritten = 0;
+        int reportBytes = 0;
+        int bytesRead;
+
+        long stime = System.currentTimeMillis();
+        while ((bytesRead = in.read(buffer)) > 0) {
+          out.write(buffer, 0, bytesRead);
+          totalBytesWritten += bytesRead;
+          reportBytes += bytesRead;
+
+          if (reportBytes >= REPORT_SIZE) {
+            context.getCounter(Counter.BYTES_COPIED).increment(reportBytes);
+            context.setStatus(String.format(statusMessage,
+                              StringUtils.humanReadableInt(totalBytesWritten),
+                              (totalBytesWritten/(float)inputFileSize) * 100.0f) +
+                              " from " + inputPath + " to " + outputPath);
+            reportBytes = 0;
+          }
+        }
+        long etime = System.currentTimeMillis();
+
+        context.getCounter(Counter.BYTES_COPIED).increment(reportBytes);
+        context.setStatus(String.format(statusMessage,
+                          StringUtils.humanReadableInt(totalBytesWritten),
+                          (totalBytesWritten/(float)inputFileSize) * 100.0f) +
+                          " from " + inputPath + " to " + outputPath);
+
+        // Verify that the written size match
+        if (totalBytesWritten != inputFileSize) {
+          String msg = "number of bytes copied not matching copied=" + totalBytesWritten +
+                       " expected=" + inputFileSize + " for file=" + inputPath;
+          throw new IOException(msg);
+        }
+
+        LOG.info("copy completed for input=" + inputPath + " output=" + outputPath);
+        LOG.info("size=" + totalBytesWritten +
+            " (" + StringUtils.humanReadableInt(totalBytesWritten) + ")" +
+            " time=" + StringUtils.formatTimeDiff(etime, stime) +
+            String.format(" %.3fM/sec", (totalBytesWritten / ((etime - stime)/1000.0))/1048576.0));
+        context.getCounter(Counter.FILES_COPIED).increment(1);
+      } catch (IOException e) {
+        LOG.error("Error copying " + inputPath + " to " + outputPath, e);
+        context.getCounter(Counter.COPY_FAILED).increment(1);
+        throw e;
+      }
+    }
+
+    /**
+     * Try to open the "source" file.
+     * Throws an IOException if the communication with the inputFs fail or
+     * if the file is not found.
+     */
+    private FSDataInputStream openSourceFile(Context context, final SnapshotFileInfo fileInfo)
+            throws IOException {
+      try {
+        Configuration conf = context.getConfiguration();
+        FileLink link = null;
+        switch (fileInfo.getType()) {
+          case HFILE:
+            Path inputPath = new Path(fileInfo.getHfile());
+            link = getFileLink(inputPath, conf);
+            break;
+          case WAL:
+            String serverName = fileInfo.getWalServer();
+            String logName = fileInfo.getWalName();
+            link = new WALLink(inputRoot, serverName, logName);
+            break;
+          default:
+            throw new IOException("Invalid File Type: " + fileInfo.getType().toString());
+        }
+        return link.open(inputFs);
+      } catch (IOException e) {
+        context.getCounter(Counter.MISSING_FILES).increment(1);
+        LOG.error("Unable to open source file=" + fileInfo.toString(), e);
+        throw e;
+      }
+    }
+
+    private FileStatus getSourceFileStatus(Context context, final SnapshotFileInfo fileInfo)
+        throws IOException {
+      try {
+        Configuration conf = context.getConfiguration();
+        FileLink link = null;
+        switch (fileInfo.getType()) {
+          case HFILE:
+            Path inputPath = new Path(fileInfo.getHfile());
+            link = getFileLink(inputPath, conf);
+            break;
+          case WAL:
+            link = new WALLink(inputRoot, fileInfo.getWalServer(), fileInfo.getWalName());
+            break;
+          default:
+            throw new IOException("Invalid File Type: " + fileInfo.getType().toString());
+        }
+        return link.getFileStatus(inputFs);
+      } catch (FileNotFoundException e) {
+        context.getCounter(Counter.MISSING_FILES).increment(1);
+        LOG.error("Unable to get the status for source file=" + fileInfo.toString(), e);
+        throw e;
+      } catch (IOException e) {
+        LOG.error("Unable to get the status for source file=" + fileInfo.toString(), e);
+        throw e;
+      }
+    }
+
+    private FileLink getFileLink(Path path, Configuration conf) throws IOException{
+      String regionName = HFileLink.getReferencedRegionName(path.getName());
+      TableName tableName = HFileLink.getReferencedTableName(path.getName());
+      if(MobUtils.getMobRegionInfo(tableName).getEncodedName().equals(regionName)) {
+        return HFileLink.buildFromHFileLinkPattern(MobUtils.getQualifiedMobRootDir(conf),
+                HFileArchiveUtil.getArchivePath(conf), path);
+      }
+      return HFileLink.buildFromHFileLinkPattern(inputRoot, inputArchive, path);
+    }
+
+    private FileChecksum getFileChecksum(final FileSystem fs, final Path path) {
+      try {
+        return fs.getFileChecksum(path);
+      } catch (IOException e) {
+        LOG.warn("Unable to get checksum for file=" + path, e);
+        return null;
+      }
+    }
+
+    /**
+     * Check if the two files are equal by looking at the file length,
+     * and at the checksum (if user has specified the verifyChecksum flag).
+     */
+    private boolean sameFile(final FileStatus inputStat, final FileStatus outputStat) {
+      // Not matching length
+      if (inputStat.getLen() != outputStat.getLen()) return false;
+
+      // Mark files as equals, since user asked for no checksum verification
+      if (!verifyChecksum) return true;
+
+      // If checksums are not available, files are not the same.
+      FileChecksum inChecksum = getFileChecksum(inputFs, inputStat.getPath());
+      if (inChecksum == null) return false;
+
+      FileChecksum outChecksum = getFileChecksum(outputFs, outputStat.getPath());
+      if (outChecksum == null) return false;
+
+      return inChecksum.equals(outChecksum);
+    }
+  }
+
+  // ==========================================================================
+  //  Input Format
+  // ==========================================================================
+
+  /**
+   * Extract the list of files (HFiles/WALs) to copy using Map-Reduce.
+   * @return list of files referenced by the snapshot (pair of path and size)
+   */
+  private static List<Pair<SnapshotFileInfo, Long>> getSnapshotFiles(final Configuration conf,
+      final FileSystem fs, final Path snapshotDir) throws IOException {
+    SnapshotDescription snapshotDesc = SnapshotDescriptionUtils.readSnapshotInfo(fs, snapshotDir);
+
+    final List<Pair<SnapshotFileInfo, Long>> files = new ArrayList<>();
+    final TableName table = TableName.valueOf(snapshotDesc.getTable());
+
+    // Get snapshot files
+    LOG.info("Loading Snapshot '" + snapshotDesc.getName() + "' hfile list");
+    SnapshotReferenceUtil.visitReferencedFiles(conf, fs, snapshotDir, snapshotDesc,
+      new SnapshotReferenceUtil.SnapshotVisitor() {
+        @Override
+        public void storeFile(final HRegionInfo regionInfo, final String family,
+            final SnapshotRegionManifest.StoreFile storeFile) throws IOException {
+          // for storeFile.hasReference() case, copied as part of the manifest
+          if (!storeFile.hasReference()) {
+            String region = regionInfo.getEncodedName();
+            String hfile = storeFile.getName();
+            Path path = HFileLink.createPath(table, region, family, hfile);
+
+            SnapshotFileInfo fileInfo = SnapshotFileInfo.newBuilder()
+              .setType(SnapshotFileInfo.Type.HFILE)
+              .setHfile(path.toString())
+              .build();
+
+            long size;
+            if (storeFile.hasFileSize()) {
+              size = storeFile.getFileSize();
+            } else {
+              size = HFileLink.buildFromHFileLinkPattern(conf, path).getFileStatus(fs).getLen();
+            }
+            files.add(new Pair<>(fileInfo, size));
+          }
+        }
+    });
+
+    return files;
+  }
+
+  /**
+   * Given a list of file paths and sizes, create around ngroups in as balanced a way as possible.
+   * The groups created will have similar amounts of bytes.
+   * <p>
+   * The algorithm used is pretty straightforward; the file list is sorted by size,
+   * and then each group fetch the bigger file available, iterating through groups
+   * alternating the direction.
+   */
+  static List<List<Pair<SnapshotFileInfo, Long>>> getBalancedSplits(
+      final List<Pair<SnapshotFileInfo, Long>> files, final int ngroups) {
+    // Sort files by size, from small to big
+    Collections.sort(files, new Comparator<Pair<SnapshotFileInfo, Long>>() {
+      public int compare(Pair<SnapshotFileInfo, Long> a, Pair<SnapshotFileInfo, Long> b) {
+        long r = a.getSecond() - b.getSecond();
+        return (r < 0) ? -1 : ((r > 0) ? 1 : 0);
+      }
+    });
+
+    // create balanced groups
+    List<List<Pair<SnapshotFileInfo, Long>>> fileGroups = new LinkedList<>();
+    long[] sizeGroups = new long[ngroups];
+    int hi = files.size() - 1;
+    int lo = 0;
+
+    List<Pair<SnapshotFileInfo, Long>> group;
+    int dir = 1;
+    int g = 0;
+
+    while (hi >= lo) {
+      if (g == fileGroups.size()) {
+        group = new LinkedList<>();
+        fileGroups.add(group);
+      } else {
+        group = fileGroups.get(g);
+      }
+
+      Pair<SnapshotFileInfo, Long> fileInfo = files.get(hi--);
+
+      // add the hi one
+      sizeGroups[g] += fileInfo.getSecond();
+      group.add(fileInfo);
+
+      // change direction when at the end or the beginning
+      g += dir;
+      if (g == ngroups) {
+        dir = -1;
+        g = ngroups - 1;
+      } else if (g < 0) {
+        dir = 1;
+        g = 0;
+      }
+    }
+
+    if (LOG.isDebugEnabled()) {
+      for (int i = 0; i < sizeGroups.length; ++i) {
+        LOG.debug("export split=" + i + " size=" + StringUtils.humanReadableInt(sizeGroups[i]));
+      }
+    }
+
+    return fileGroups;
+  }
+
+  private static class ExportSnapshotInputFormat extends InputFormat<BytesWritable, NullWritable> {
+    @Override
+    public RecordReader<BytesWritable, NullWritable> createRecordReader(InputSplit split,
+        TaskAttemptContext tac) throws IOException, InterruptedException {
+      return new ExportSnapshotRecordReader(((ExportSnapshotInputSplit)split).getSplitKeys());
+    }
+
+    @Override
+    public List<InputSplit> getSplits(JobContext context) throws IOException, InterruptedException {
+      Configuration conf = context.getConfiguration();
+      Path snapshotDir = new Path(conf.get(CONF_SNAPSHOT_DIR));
+      FileSystem fs = FileSystem.get(snapshotDir.toUri(), conf);
+
+      List<Pair<SnapshotFileInfo, Long>> snapshotFiles = getSnapshotFiles(conf, fs, snapshotDir);
+      int mappers = conf.getInt(CONF_NUM_SPLITS, 0);
+      if (mappers == 0 && snapshotFiles.size() > 0) {
+        mappers = 1 + (snapshotFiles.size() / conf.getInt(CONF_MAP_GROUP, 10));
+        mappers = Math.min(mappers, snapshotFiles.size());
+        conf.setInt(CONF_NUM_SPLITS, mappers);
+        conf.setInt(MR_NUM_MAPS, mappers);
+      }
+
+      List<List<Pair<SnapshotFileInfo, Long>>> groups = getBalancedSplits(snapshotFiles, mappers);
+      List<InputSplit> splits = new ArrayList(groups.size());
+      for (List<Pair<SnapshotFileInfo, Long>> files: groups) {
+        splits.add(new ExportSnapshotInputSplit(files));
+      }
+      return splits;
+    }
+
+    private static class ExportSnapshotInputSplit extends InputSplit implements Writable {
+      private List<Pair<BytesWritable, Long>> files;
+      private long length;
+
+      public ExportSnapshotInputSplit() {
+        this.files = null;
+      }
+
+      public ExportSnapshotInputSplit(final List<Pair<SnapshotFileInfo, Long>> snapshotFiles) {
+        this.files = new ArrayList(snapshotFiles.size());
+        for (Pair<SnapshotFileInfo, Long> fileInfo: snapshotFiles) {
+          this.files.add(new Pair<>(
+            new BytesWritable(fileInfo.getFirst().toByteArray()), fileInfo.getSecond()));
+          this.length += fileInfo.getSecond();
+        }
+      }
+
+      private List<Pair<BytesWritable, Long>> getSplitKeys() {
+        return files;
+      }
+
+      @Override
+      public long getLength() throws IOException, InterruptedException {
+        return length;
+      }
+
+      @Override
+      public String[] getLocations() throws IOException, InterruptedException {
+        return new String[] {};
+      }
+
+      @Override
+      public void readFields(DataInput in) throws IOException {
+        int count = in.readInt();
+        files = new ArrayList<>(count);
+        length = 0;
+        for (int i = 0; i < count; ++i) {
+          BytesWritable fileInfo = new BytesWritable();
+          fileInfo.readFields(in);
+          long size = in.readLong();
+          files.add(new Pair<>(fileInfo, size));
+          length += size;
+        }
+      }
+
+      @Override
+      public void write(DataOutput out) throws IOException {
+        out.writeInt(files.size());
+        for (final Pair<BytesWritable, Long> fileInfo: files) {
+          fileInfo.getFirst().write(out);
+          out.writeLong(fileInfo.getSecond());
+        }
+      }
+    }
+
+    private static class ExportSnapshotRecordReader
+        extends RecordReader<BytesWritable, NullWritable> {
+      private final List<Pair<BytesWritable, Long>> files;
+      private long totalSize = 0;
+      private long procSize = 0;
+      private int index = -1;
+
+      ExportSnapshotRecordReader(final List<Pair<BytesWritable, Long>> files) {
+        this.files = files;
+        for (Pair<BytesWritable, Long> fileInfo: files) {
+          totalSize += fileInfo.getSecond();
+        }
+      }
+
+      @Override
+      public void close() { }
+
+      @Override
+      public BytesWritable getCurrentKey() { return files.get(index).getFirst(); }
+
+      @Override
+      public NullWritable getCurrentValue() { return NullWritable.get(); }
+
+      @Override
+      public float getProgress() { return (float)procSize / totalSize; }
+
+      @Override
+      public void initialize(InputSplit split, TaskAttemptContext tac) { }
+
+      @Override
+      public boolean nextKeyValue() {
+        if (index >= 0) {
+          procSize += files.get(index).getSecond();
+        }
+        return(++index < files.size());
+      }
+    }
+  }
+
+  // ==========================================================================
+  //  Tool
+  // ==========================================================================
+
+  /**
+   * Run Map-Reduce Job to perform the files copy.
+   */
+  private void runCopyJob(final Path inputRoot, final Path outputRoot,
+      final String snapshotName, final Path snapshotDir, final boolean verifyChecksum,
+      final String filesUser, final String filesGroup, final int filesMode,
+      final int mappers, final int bandwidthMB)
+          throws IOException, InterruptedException, ClassNotFoundException {
+    Configuration conf = getConf();
+    if (filesGroup != null) conf.set(CONF_FILES_GROUP, filesGroup);
+    if (filesUser != null) conf.set(CONF_FILES_USER, filesUser);
+    if (mappers > 0) {
+      conf.setInt(CONF_NUM_SPLITS, mappers);
+      conf.setInt(MR_NUM_MAPS, mappers);
+    }
+    conf.setInt(CONF_FILES_MODE, filesMode);
+    conf.setBoolean(CONF_CHECKSUM_VERIFY, verifyChecksum);
+    conf.set(CONF_OUTPUT_ROOT, outputRoot.toString());
+    conf.set(CONF_INPUT_ROOT, inputRoot.toString());
+    conf.setInt(CONF_BANDWIDTH_MB, bandwidthMB);
+    conf.set(CONF_SNAPSHOT_NAME, snapshotName);
+    conf.set(CONF_SNAPSHOT_DIR, snapshotDir.toString());
+
+    Job job = new Job(conf);
+    job.setJobName("ExportSnapshot-" + snapshotName);
+    job.setJarByClass(ExportSnapshot.class);
+    TableMapReduceUtil.addDependencyJars(job);
+    job.setMapperClass(ExportMapper.class);
+    job.setInputFormatClass(ExportSnapshotInputFormat.class);
+    job.setOutputFormatClass(NullOutputFormat.class);
+    job.setMapSpeculativeExecution(false);
+    job.setNumReduceTasks(0);
+
+    // Acquire the delegation Tokens
+    Configuration srcConf = HBaseConfiguration.createClusterConf(conf, null, CONF_SOURCE_PREFIX);
+    TokenCache.obtainTokensForNamenodes(job.getCredentials(),
+      new Path[] { inputRoot }, srcConf);
+    Configuration destConf = HBaseConfiguration.createClusterConf(conf, null, CONF_DEST_PREFIX);
+    TokenCache.obtainTokensForNamenodes(job.getCredentials(),
+        new Path[] { outputRoot }, destConf);
+
+    // Run the MR Job
+    if (!job.waitForCompletion(true)) {
+      // TODO: Replace the fixed string with job.getStatus().getFailureInfo()
+      // when it will be available on all the supported versions.
+      throw new ExportSnapshotException("Copy Files Map-Reduce Job failed");
+    }
+  }
+
+  private void verifySnapshot(final Configuration baseConf,
+      final FileSystem fs, final Path rootDir, final Path snapshotDir) throws IOException {
+    // Update the conf with the current root dir, since may be a different cluster
+    Configuration conf = new Configuration(baseConf);
+    FSUtils.setRootDir(conf, rootDir);
+    FSUtils.setFsDefault(conf, FSUtils.getRootDir(conf));
+    SnapshotDescription snapshotDesc = SnapshotDescriptionUtils.readSnapshotInfo(fs, snapshotDir);
+    SnapshotReferenceUtil.verifySnapshot(conf, fs, snapshotDir, snapshotDesc);
+  }
+
+  /**
+   * Set path ownership.
+   */
+  private void setOwner(final FileSystem fs, final Path path, final String user,
+      final String group, final boolean recursive) throws IOException {
+    if (user != null || group != null) {
+      if (recursive && fs.isDirectory(path)) {
+        for (FileStatus child : fs.listStatus(path)) {
+          setOwner(fs, child.getPath(), user, group, recursive);
+        }
+      }
+      fs.setOwner(path, user, group);
+    }
+  }
+
+  /**
+   * Set path permission.
+   */
+  private void setPermission(final FileSystem fs, final Path path, final short filesMode,
+      final boolean recursive) throws IOException {
+    if (filesMode > 0) {
+      FsPermission perm = new FsPermission(filesMode);
+      if (recursive && fs.isDirectory(path)) {
+        for (FileStatus child : fs.listStatus(path)) {
+          setPermission(fs, child.getPath(), filesMode, recursive);
+        }
+      }
+      fs.setPermission(path, perm);
+    }
+  }
+
+  private boolean verifyTarget = true;
+  private boolean verifyChecksum = true;
+  private String snapshotName = null;
+  private String targetName = null;
+  private boolean overwrite = false;
+  private String filesGroup = null;
+  private String filesUser = null;
+  private Path outputRoot = null;
+  private Path inputRoot = null;
+  private int bandwidthMB = Integer.MAX_VALUE;
+  private int filesMode = 0;
+  private int mappers = 0;
+
+  @Override
+  protected void processOptions(CommandLine cmd) {
+    snapshotName = cmd.getOptionValue(Options.SNAPSHOT.getLongOpt(), snapshotName);
+    targetName = cmd.getOptionValue(Options.TARGET_NAME.getLongOpt(), targetName);
+    if (cmd.hasOption(Options.COPY_TO.getLongOpt())) {
+      outputRoot = new Path(cmd.getOptionValue(Options.COPY_TO.getLongOpt()));
+    }
+    if (cmd.hasOption(Options.COPY_FROM.getLongOpt())) {
+      inputRoot = new Path(cmd.getOptionValue(Options.COPY_FROM.getLongOpt()));
+    }
+    mappers = getOptionAsInt(cmd, Options.MAPPERS.getLongOpt(), mappers);
+    filesUser = cmd.getOptionValue(Options.CHUSER.getLongOpt(), filesUser);
+    filesGroup = cmd.getOptionValue(Options.CHGROUP.getLongOpt(), filesGroup);
+    filesMode = getOptionAsInt(cmd, Options.CHMOD.getLongOpt(), filesMode);
+    bandwidthMB = getOptionAsInt(cmd, Options.BANDWIDTH.getLongOpt(), bandwidthMB);
+    overwrite = cmd.hasOption(Options.OVERWRITE.getLongOpt());
+    // And verifyChecksum and verifyTarget with values read from old args in processOldArgs(...).
+    verifyChecksum = !cmd.hasOption(Options.NO_CHECKSUM_VERIFY.getLongOpt());
+    verifyTarget = !cmd.hasOption(Options.NO_TARGET_VERIFY.getLongOpt());
+  }
+
+  /**
+   * Execute the export snapshot by copying the snapshot metadata, hfiles and wals.
+   * @return 0 on success, and != 0 upon failure.
+   */
+  @Override
+  public int doWork() throws IOException {
+    Configuration conf = getConf();
+
+    // Check user options
+    if (snapshotName == null) {
+      System.err.println("Snapshot name not provided.");
+      LOG.error("Use -h or --help for usage instructions.");
+      return 0;
+    }
+
+    if (outputRoot == null) {
+      System.err.println("Destination file-system (--" + Options.COPY_TO.getLongOpt()
+              + ") not provided.");
+      LOG.error("Use -h or --help for usage instructions.");
+      return 0;
+    }
+
+    if (targetName == null) {
+      targetName = snapshotName;
+    }
+    if (inputRoot == null) {
+      inputRoot = FSUtils.getRootDir(conf);
+    } else {
+      FSUtils.setRootDir(conf, inputRoot);
+    }
+
+    Configuration srcConf = HBaseConfiguration.createClusterConf(conf, null, CONF_SOURCE_PREFIX);
+    srcConf.setBoolean("fs." + inputRoot.toUri().getScheme() + ".impl.disable.cache", true);
+    FileSystem inputFs = FileSystem.get(inputRoot.toUri(), srcConf);
+    LOG.debug("inputFs=" + inputFs.getUri().toString() + " inputRoot=" + inputRoot);
+    Configuration destConf = HBaseConfiguration.createClusterConf(conf, null, CONF_DEST_PREFIX);
+    destConf.setBoolean("fs." + outputRoot.toUri().getScheme() + ".impl.disable.cache", true);
+    FileSystem outputFs = FileSystem.get(outputRoot.toUri(), destConf);
+    LOG.debug("outputFs=" + outputFs.getUri().toString() + " outputRoot=" + outputRoot.toString());
+
+    boolean skipTmp = conf.getBoolean(CONF_SKIP_TMP, false);
+
+    Path snapshotDir = SnapshotDescriptionUtils.getCompletedSnapshotDir(snapshotName, inputRoot);
+    Path snapshotTmpDir = SnapshotDescriptionUtils.getWorkingSnapshotDir(targetName, outputRoot);
+    Path outputSnapshotDir = SnapshotDescriptionUtils.getCompletedSnapshotDir(targetName, outputRoot);
+    Path initialOutputSnapshotDir = skipTmp ? outputSnapshotDir : snapshotTmpDir;
+
+    // Find the necessary directory which need to change owner and group
+    Path needSetOwnerDir = SnapshotDescriptionUtils.getSnapshotRootDir(outputRoot);
+    if (outputFs.exists(needSetOwnerDir)) {
+      if (skipTmp) {
+        needSetOwnerDir = outputSnapshotDir;
+      } else {
+        needSetOwnerDir = SnapshotDescriptionUtils.getWorkingSnapshotDir(outputRoot);
+        if (outputFs.exists(needSetOwnerDir)) {
+          needSetOwnerDir = snapshotTmpDir;
+        }
+      }
+    }
+
+    // Check if the snapshot already exists
+    if (outputFs.exists(outputSnapshotDir)) {
+      if (overwrite) {
+        if (!outputFs.delete(outputSnapshotDir, true)) {
+          System.err.println("Unable to remove existing snapshot directory: " + outputSnapshotDir);
+          return 1;
+        }
+      } else {
+        System.err.println("The snapshot '" + targetName +
+          "' already exists in the destination: " + outputSnapshotDir);
+        return 1;
+      }
+    }
+
+    if (!skipTmp) {
+      // Check if the snapshot already in-progress
+      if (outputFs.exists(snapshotTmpDir)) {
+        if (overwrite) {
+          if (!outputFs.delete(snapshotTmpDir, true)) {
+            System.err.println("Unable to remove existing snapshot tmp directory: "+snapshotTmpDir);
+            return 1;
+          }
+        } else {
+          System.err.println("A snapshot with the same name '"+ targetName +"' may be in-progress");
+          System.err.println("Please check "+snapshotTmpDir+". If the snapshot has completed, ");
+          System.err.println("consider removing "+snapshotTmpDir+" by using the -overwrite option");
+          return 1;
+        }
+      }
+    }
+
+    // Step 1 - Copy fs1:/.snapshot/<snapshot> to  fs2:/.snapshot/.tmp/<snapshot>
+    // The snapshot references must be copied before the hfiles otherwise the cleaner
+    // will remove them because they are unreferenced.
+    try {
+      LOG.info("Copy Snapshot Manifest");
+      FileUtil.copy(inputFs, snapshotDir, outputFs, initialOutputSnapshotDir, false, false, conf);
+    } catch (IOException e) {
+      throw new ExportSnapshotException("Failed to copy the snapshot directory: from=" +
+        snapshotDir + " to=" + initialOutputSnapshotDir, e);
+    } finally {
+      if (filesUser != null || filesGroup != null) {
+        LOG.warn((filesUser == null ? "" : "Change the owner of " + needSetOwnerDir + " to "
+            + filesUser)
+            + (filesGroup == null ? "" : ", Change the group of " + needSetOwnerDir + " to "
+            + filesGroup));
+        setOwner(outputFs, needSetOwnerDir, filesUser, filesGroup, true);
+      }
+      if (filesMode > 0) {
+        LOG.warn("Change the permission of " + needSetOwnerDir + " to " + filesMode);
+        setPermission(outputFs, needSetOwnerDir, (short)filesMode, true);
+      }
+    }
+
+    // Write a new .snapshotinfo if the target name is different from the source name
+    if (!targetName.equals(snapshotName)) {
+      SnapshotDescription snapshotDesc =
+        SnapshotDescriptionUtils.readSnapshotInfo(inputFs, snapshotDir)
+          .toBuilder()
+          .setName(targetName)
+          .build();
+      SnapshotDescriptionUtils.writeSnapshotInfo(snapshotDesc, initialOutputSnapshotDir, outputFs);
+      if (filesUser != null || filesGroup != null) {
+        outputFs.setOwner(new Path(initialOutputSnapshotDir,
+          SnapshotDescriptionUtils.SNAPSHOTINFO_FILE), filesUser, filesGroup);
+      }
+      if (filesMode > 0) {
+        outputFs.setPermission(new Path(initialOutputSnapshotDir,
+          SnapshotDescriptionUtils.SNAPSHOTINFO_FILE), new FsPermission((short)filesMode));
+      }
+    }
+
+    // Step 2 - Start MR Job to copy files
+    // The snapshot references must be copied before the files otherwise the files gets removed
+    // by the HFileArchiver, since they have no references.
+    try {
+      runCopyJob(inputRoot, outputRoot, snapshotName, snapshotDir, verifyChecksum,
+                 filesUser, filesGroup, filesMode, mappers, bandwidthMB);
+
+      LOG.info("Finalize the Snapshot Export");
+      if (!skipTmp) {
+        // Step 3 - Rename fs2:/.snapshot/.tmp/<snapshot> fs2:/.snapshot/<snapshot>
+        if (!outputFs.rename(snapshotTmpDir, outputSnapshotDir)) {
+          throw new ExportSnapshotException("Unable to rename snapshot directory from=" +
+            snapshotTmpDir + " to=" + outputSnapshotDir);
+        }
+      }
+
+      // Step 4 - Verify snapshot integrity
+      if (verifyTarget) {
+        LOG.info("Verify snapshot integrity");
+        verifySnapshot(destConf, outputFs, outputRoot, outputSnapshotDir);
+      }
+
+      LOG.info("Export Completed: " + targetName);
+      return 0;
+    } catch (Exception e) {
+      LOG.error("Snapshot export failed", e);
+      if (!skipTmp) {
+        outputFs.delete(snapshotTmpDir, true);
+      }
+      outputFs.delete(outputSnapshotDir, true);
+      return 1;
+    } finally {
+      IOUtils.closeStream(inputFs);
+      IOUtils.closeStream(outputFs);
+    }
+  }
+
+  @Override
+  protected void printUsage() {
+    super.printUsage();
+    System.out.println("\n"
+        + "Examples:\n"
+        + "  hbase snapshot export \\\n"
+        + "    --snapshot MySnapshot --copy-to hdfs://srv2:8082/hbase \\\n"
+        + "    --chuser MyUser --chgroup MyGroup --chmod 700 --mappers 16\n"
+        + "\n"
+        + "  hbase snapshot export \\\n"
+        + "    --snapshot MySnapshot --copy-from hdfs://srv2:8082/hbase \\\n"
+        + "    --copy-to hdfs://srv1:50070/hbase");
+  }
+
+  @Override protected void addOptions() {
+    addRequiredOption(Options.SNAPSHOT);
+    addOption(Options.COPY_TO);
+    addOption(Options.COPY_FROM);
+    addOption(Options.TARGET_NAME);
+    addOption(Options.NO_CHECKSUM_VERIFY);
+    addOption(Options.NO_TARGET_VERIFY);
+    addOption(Options.OVERWRITE);
+    addOption(Options.CHUSER);
+    addOption(Options.CHGROUP);
+    addOption(Options.CHMOD);
+    addOption(Options.MAPPERS);
+    addOption(Options.BANDWIDTH);
+  }
+
+  public static void main(String[] args) {
+    new ExportSnapshot().doStaticMain(args);
+  }
+}

http://git-wip-us.apache.org/repos/asf/hbase/blob/664b6be0/hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/util/MapreduceDependencyClasspathTool.java
----------------------------------------------------------------------
diff --git a/hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/util/MapreduceDependencyClasspathTool.java b/hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/util/MapreduceDependencyClasspathTool.java
new file mode 100644
index 0000000..e8f073d
--- /dev/null
+++ b/hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/util/MapreduceDependencyClasspathTool.java
@@ -0,0 +1,73 @@
+/**
+ * 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.hbase.util;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.HBaseConfiguration;
+import org.apache.hadoop.hbase.HBaseInterfaceAudience;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;
+import org.apache.hadoop.util.Tool;
+import org.apache.hadoop.util.ToolRunner;
+import org.apache.log4j.Level;
+import org.apache.log4j.Logger;
+
+/**
+ * Generate a classpath string containing any jars required by mapreduce jobs. Specify
+ * additional values by providing a comma-separated list of paths via -Dtmpjars.
+ */
+@InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.TOOLS)
+public class MapreduceDependencyClasspathTool implements Tool {
+
+  private Configuration conf;
+
+  @Override
+  public void setConf(Configuration conf) {
+    this.conf = conf;
+  }
+
+  @Override
+  public Configuration getConf() {
+    return conf;
+  }
+
+  @Override
+  public int run(String[] args) throws Exception {
+    if (args.length > 0) {
+      System.err.println("Usage: hbase mapredcp [-Dtmpjars=...]");
+      System.err.println("  Construct a CLASSPATH containing dependency jars required to run a mapreduce");
+      System.err.println("  job. By default, includes any jars detected by TableMapReduceUtils. Provide");
+      System.err.println("  additional entries by specifying a comma-separated list in tmpjars.");
+      return 0;
+    }
+
+    TableMapReduceUtil.addHBaseDependencyJars(getConf());
+    System.out.println(TableMapReduceUtil.buildDependencyClasspath(getConf()));
+    return 0;
+  }
+
+  public static void main(String[] argv) throws Exception {
+    // Silence the usual noise. This is probably fragile...
+    Logger logger = Logger.getLogger("org.apache.hadoop.hbase");
+    if (logger != null) {
+      logger.setLevel(Level.WARN);
+    }
+    System.exit(ToolRunner.run(
+      HBaseConfiguration.create(), new MapreduceDependencyClasspathTool(), argv));
+  }
+}


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