/**
* 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.namenode;
import static org.apache.hadoop.hdfs.protocol.FSConstants.BUFFER_SIZE;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.security.DigestInputStream;
import java.security.MessageDigest;
import java.security.PrivilegedAction;
import java.security.PrivilegedExceptionAction;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hdfs.DFSConfigKeys;
import org.apache.hadoop.hdfs.server.common.HdfsConstants;
import org.apache.hadoop.hdfs.server.common.InconsistentFSStateException;
import org.apache.hadoop.hdfs.server.protocol.NamenodeProtocol;
import org.apache.hadoop.http.HttpServer;
import org.apache.hadoop.io.MD5Hash;
import org.apache.hadoop.ipc.RPC;
import org.apache.hadoop.ipc.RemoteException;
import org.apache.hadoop.metrics2.source.JvmMetricsSource;
import org.apache.hadoop.net.NetUtils;
import org.apache.hadoop.security.Krb5AndCertsSslSocketConnector;
import org.apache.hadoop.security.SecurityUtil;
import org.apache.hadoop.security.UserGroupInformation;
import org.apache.hadoop.security.authentication.server.AuthenticationFilter;
import org.apache.hadoop.util.Daemon;
import org.apache.hadoop.util.StringUtils;
/**********************************************************
* The Secondary NameNode is a helper to the primary NameNode.
* The Secondary is responsible for supporting periodic checkpoints
* of the HDFS metadata. The current design allows only one Secondary
* NameNode per HDFs cluster.
*
* The Secondary NameNode is a daemon that periodically wakes
* up (determined by the schedule specified in the configuration),
* triggers a periodic checkpoint and then goes back to sleep.
* The Secondary NameNode uses the ClientProtocol to talk to the
* primary NameNode.
*
**********************************************************/
public class SecondaryNameNode implements Runnable {
static{
Configuration.addDefaultResource("hdfs-default.xml");
Configuration.addDefaultResource("hdfs-site.xml");
}
public static final Log LOG =
LogFactory.getLog(SecondaryNameNode.class.getName());
private final long starttime = System.currentTimeMillis();
private volatile long lastCheckpointTime = 0;
private String fsName;
private CheckpointStorage checkpointImage;
private NamenodeProtocol namenode;
private Configuration conf;
private InetSocketAddress nameNodeAddr;
private volatile boolean shouldRun;
private HttpServer infoServer;
private int infoPort;
private int imagePort;
private String infoBindAddress;
private Collection<File> checkpointDirs;
private Collection<File> checkpointEditsDirs;
private long checkpointPeriod; // in seconds
private long checkpointSize; // size (in bytes) of current Edit Log
/** {@inheritDoc} */
public String toString() {
return getClass().getSimpleName() + " Status"
+ "\nName Node Address : " + nameNodeAddr
+ "\nStart Time : " + new Date(starttime)
+ "\nLast Checkpoint Time : " + (lastCheckpointTime == 0? "--": new Date(lastCheckpointTime))
+ "\nCheckpoint Period : " + checkpointPeriod + " seconds"
+ "\nCheckpoint Size : " + StringUtils.byteDesc(checkpointSize)
+ " (= " + checkpointSize + " bytes)"
+ "\nCheckpoint Dirs : " + checkpointDirs
+ "\nCheckpoint Edits Dirs: " + checkpointEditsDirs;
}
/**
* Utility class to facilitate junit test error simulation.
*/
static class ErrorSimulator {
private static boolean[] simulation = null; // error simulation events
static void initializeErrorSimulationEvent(int numberOfEvents) {
simulation = new boolean[numberOfEvents];
for (int i = 0; i < numberOfEvents; i++) {
simulation[i] = false;
}
}
static boolean getErrorSimulation(int index) {
if(simulation == null)
return false;
assert(index < simulation.length);
return simulation[index];
}
static void setErrorSimulation(int index) {
assert(index < simulation.length);
simulation[index] = true;
}
static void clearErrorSimulation(int index) {
assert(index < simulation.length);
simulation[index] = false;
}
}
FSImage getFSImage() {
return checkpointImage;
}
/**
* Create a connection to the primary namenode.
*/
public SecondaryNameNode(Configuration conf) throws IOException {
try {
initialize(conf);
} catch(IOException e) {
shutdown();
throw e;
}
}
@SuppressWarnings("deprecation")
public static InetSocketAddress getHttpAddress(Configuration conf) {
String infoAddr = NetUtils.getServerAddress(conf,
"dfs.secondary.info.bindAddress", "dfs.secondary.info.port",
"dfs.secondary.http.address");
return NetUtils.createSocketAddr(infoAddr);
}
/**
* Initialize SecondaryNameNode.
*/
private void initialize(final Configuration conf) throws IOException {
//SecondaryNameNode should not tolerate any corruption
//since edit logs are transferred from a healthy NameNode.
final int editsTolerationLength = conf.getInt(
DFSConfigKeys.DFS_NAMENODE_EDITS_TOLERATION_LENGTH_KEY,
DFSConfigKeys.DFS_NAMENODE_EDITS_TOLERATION_LENGTH_DEFAULT);
if (editsTolerationLength >= 0) {
LOG.info(DFSConfigKeys.DFS_NAMENODE_EDITS_TOLERATION_LENGTH_KEY
+ " is set to " + editsTolerationLength
+ ". Override it with -1, i.e. disable it.");
conf.setInt(DFSConfigKeys.DFS_NAMENODE_EDITS_TOLERATION_LENGTH_KEY, -1);
}
final InetSocketAddress infoSocAddr = getHttpAddress(conf);
infoBindAddress = infoSocAddr.getHostName();
if (UserGroupInformation.isSecurityEnabled()) {
SecurityUtil.login(conf,
DFSConfigKeys.DFS_SECONDARY_NAMENODE_KEYTAB_FILE_KEY,
DFSConfigKeys.DFS_SECONDARY_NAMENODE_USER_NAME_KEY,
infoBindAddress);
}
// initiate Java VM metrics
JvmMetricsSource.create("SecondaryNameNode", conf.get("session.id"));
// Create connection to the namenode.
shouldRun = true;
nameNodeAddr = NameNode.getServiceAddress(conf, true);
this.conf = conf;
this.namenode =
(NamenodeProtocol) RPC.waitForProxy(NamenodeProtocol.class,
NamenodeProtocol.versionID, nameNodeAddr, conf);
// initialize checkpoint directories
fsName = getInfoServer();
checkpointDirs = FSImage.getCheckpointDirs(conf,
"/tmp/hadoop/dfs/namesecondary");
checkpointEditsDirs = FSImage.getCheckpointEditsDirs(conf,
"/tmp/hadoop/dfs/namesecondary");
checkpointImage = new CheckpointStorage();
checkpointImage.recoverCreate(checkpointDirs, checkpointEditsDirs);
// Initialize other scheduling parameters from the configuration
checkpointPeriod = conf.getLong("fs.checkpoint.period", 3600);
checkpointSize = conf.getLong("fs.checkpoint.size", 4194304);
// initialize the webserver for uploading files.
if (SecurityUtil.useKsslAuth()) {
initializeKsslWebServer(infoSocAddr);
} else {
initializeHttpWebServer(infoSocAddr);
}
LOG.info("Web server init done");
// The web-server port can be ephemeral... ensure we have the correct info
infoPort = infoServer.getPort();
if (!SecurityUtil.useKsslAuth()) {
imagePort = infoPort;
}
conf.set("dfs.secondary.http.address", infoBindAddress + ":" +infoPort);
LOG.info("Secondary Web-server up at: " + infoBindAddress + ":" +infoPort);
LOG.warn("Checkpoint Period :" + checkpointPeriod + " secs " +
"(" + checkpointPeriod/60 + " min)");
LOG.warn("Log Size Trigger :" + checkpointSize + " bytes " +
"(" + checkpointSize/1024 + " KB)");
}
private void initializeHttpWebServer(final InetSocketAddress infoSocAddr)
throws IOException {
int tmpInfoPort = infoSocAddr.getPort();
infoServer = new HttpServer("secondary", infoBindAddress, tmpInfoPort,
tmpInfoPort == 0, conf,
SecurityUtil.getAdminAcls
(conf, DFSConfigKeys.DFS_ADMIN)) {
{
if (UserGroupInformation.isSecurityEnabled()) {
// Security is enabled, so use SPNEGO to authenticate.
Map<String, String> params = new HashMap<String, String>();
String principalInConf =
conf.get(DFSConfigKeys.DFS_SECONDARY_NAMENODE_INTERNAL_SPENGO_USER_NAME_KEY);
if (principalInConf != null && !principalInConf.isEmpty()) {
params.put("kerberos.principal",
SecurityUtil.getServerPrincipal
(principalInConf, infoSocAddr.getHostName()));
}
String httpKeytab = conf.get(
DFSConfigKeys.DFS_WEB_AUTHENTICATION_KERBEROS_KEYTAB_KEY);
if (null == httpKeytab) {
httpKeytab = conf.get(
DFSConfigKeys.DFS_SECONDARY_NAMENODE_KEYTAB_FILE_KEY);
}
if (httpKeytab != null && !httpKeytab.isEmpty()) {
params.put("kerberos.keytab", httpKeytab);
}
params.put(AuthenticationFilter.AUTH_TYPE, "kerberos");
defineFilter(webAppContext, SPNEGO_FILTER,
AuthenticationFilter.class.getName(),
params, null);
}
}
};
infoServer.setAttribute("secondary.name.node", this);
infoServer.setAttribute("name.system.image", checkpointImage);
infoServer.setAttribute(JspHelper.CURRENT_CONF, conf);
infoServer.addInternalServlet("getimage", "/getimage",
GetImageServlet.class, true, false);
infoServer.start();
}
private void initializeKsslWebServer(final InetSocketAddress infoSocAddr)
throws IOException {
// Kerberized SSL servers must be run from the host principal...
UserGroupInformation httpUGI =
UserGroupInformation.loginUserFromKeytabAndReturnUGI(
SecurityUtil.getServerPrincipal(conf
.get(DFSConfigKeys.DFS_SECONDARY_NAMENODE_KRB_HTTPS_USER_NAME_KEY),
infoBindAddress),
conf.get(DFSConfigKeys.DFS_SECONDARY_NAMENODE_KEYTAB_FILE_KEY));
try {
infoServer = httpUGI.doAs(new PrivilegedExceptionAction<HttpServer>() {
@Override
public HttpServer run() throws IOException, InterruptedException {
LOG.info("Starting web server as: " +
UserGroupInformation.getCurrentUser().getUserName());
int tmpInfoPort = infoSocAddr.getPort();
infoServer = new HttpServer("secondary", infoBindAddress, tmpInfoPort,
tmpInfoPort == 0, conf,
SecurityUtil.getAdminAcls(conf, DFSConfigKeys.DFS_ADMIN));
System.setProperty("https.cipherSuites",
Krb5AndCertsSslSocketConnector.KRB5_CIPHER_SUITES.get(0));
InetSocketAddress secInfoSocAddr =
NetUtils.createSocketAddr(infoBindAddress + ":"+ conf.getInt(
"dfs.secondary.https.port", 50490));
imagePort = secInfoSocAddr.getPort();
infoServer.addSslListener(secInfoSocAddr, conf, false, true);
infoServer.setAttribute("name.system.image", checkpointImage);
infoServer.setAttribute(JspHelper.CURRENT_CONF, conf);
infoServer.addInternalServlet("getimage", "/getimage",
GetImageServlet.class, true, true);
infoServer.start();
return infoServer;
}
});
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
}
/**
* Shut down this instance of the datanode.
* Returns only after shutdown is complete.
*/
public void shutdown() {
shouldRun = false;
try {
if (infoServer != null) infoServer.stop();
} catch (Exception e) {
LOG.warn("Exception shutting down SecondaryNameNode", e);
}
try {
if (checkpointImage != null) checkpointImage.close();
} catch(IOException e) {
LOG.warn(StringUtils.stringifyException(e));
}
}
public void run() {
if (UserGroupInformation.isSecurityEnabled()) {
UserGroupInformation ugi = null;
try {
ugi = UserGroupInformation.getLoginUser();
} catch (IOException e) {
LOG.error(StringUtils.stringifyException(e));
e.printStackTrace();
Runtime.getRuntime().exit(-1);
}
ugi.doAs(new PrivilegedAction<Object>() {
@Override
public Object run() {
doWork();
return null;
}
});
} else {
doWork();
}
}
//
// The main work loop
//
public void doWork() {
//
// Poll the Namenode (once every 5 minutes) to find the size of the
// pending edit log.
//
long period = 5 * 60; // 5 minutes
if (checkpointPeriod < period) {
period = checkpointPeriod;
}
while (shouldRun) {
try {
Thread.sleep(1000 * period);
} catch (InterruptedException ie) {
// do nothing
}
if (!shouldRun) {
break;
}
try {
// We may have lost our ticket since last checkpoint, log in again, just in case
if(UserGroupInformation.isSecurityEnabled())
UserGroupInformation.getCurrentUser().reloginFromKeytab();
long now = System.currentTimeMillis();
long size = namenode.getEditLogSize();
if (size >= checkpointSize ||
now >= lastCheckpointTime + 1000 * checkpointPeriod) {
doCheckpoint();
lastCheckpointTime = now;
}
} catch (IOException e) {
LOG.error("Exception in doCheckpoint: ");
LOG.error(StringUtils.stringifyException(e));
e.printStackTrace();
} catch (Throwable e) {
LOG.error("Throwable Exception in doCheckpoint: ");
LOG.error(StringUtils.stringifyException(e));
e.printStackTrace();
Runtime.getRuntime().exit(-1);
}
}
}
/**
* Download <code>fsimage</code> and <code>edits</code>
* files from the name-node.
* @throws IOException
*/
private void downloadCheckpointFiles(final CheckpointSignature sig
) throws IOException {
try {
UserGroupInformation.getCurrentUser().doAs(new PrivilegedExceptionAction<Void>() {
@Override
public Void run() throws Exception {
checkpointImage.cTime = sig.cTime;
checkpointImage.checkpointTime = sig.checkpointTime;
// get fsimage
String fileid = "getimage=1";
File[] srcNames = checkpointImage.getImageFiles();
assert srcNames.length > 0 : "No checkpoint targets.";
TransferFsImage.getFileClient(fsName, fileid, srcNames, false);
LOG.info("Downloaded file " + srcNames[0].getName() + " size " +
srcNames[0].length() + " bytes.");
// get edits file
fileid = "getedit=1";
srcNames = checkpointImage.getEditsFiles();
assert srcNames.length > 0 : "No checkpoint targets.";
TransferFsImage.getFileClient(fsName, fileid, srcNames, false);
LOG.info("Downloaded file " + srcNames[0].getName() + " size " +
srcNames[0].length() + " bytes.");
checkpointImage.checkpointUploadDone();
return null;
}
});
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
}
/**
* Copy the new fsimage into the NameNode
*/
private void putFSImage(CheckpointSignature sig) throws IOException {
String fileid = "putimage=1&port=" + imagePort +
"&machine=" + infoBindAddress +
"&token=" + sig.toString() +
"&newChecksum=" + getNewChecksum();
LOG.info("Posted URL " + fsName + fileid);
TransferFsImage.getFileClient(fsName, fileid, (File[])null, false);
}
/**
* Calculate the MD5 hash of the newly-merged fsimage.
* @return the checksum of the newly-merged fsimage.
*/
MD5Hash getNewChecksum() throws IOException {
DigestInputStream imageIn = null;
try {
MessageDigest digester = MD5Hash.getDigester();
imageIn = new DigestInputStream(
new FileInputStream(checkpointImage.getFsImageName()), digester);
byte[] in = new byte[BUFFER_SIZE];
int totalRead = 0;
int read = 0;
while ((read = imageIn.read(in)) > 0) {
totalRead += read;
LOG.debug("Computing fsimage checksum. Read " + totalRead + " bytes so far.");
}
return new MD5Hash(digester.digest());
} finally {
if (imageIn != null) {
imageIn.close();
}
}
}
/**
* Returns the Jetty server that the Namenode is listening on.
*/
private String getInfoServer() throws IOException {
String infoAddr = NameNode.getInfoServer(conf);
if (infoAddr == null) {
throw new IOException("This is not a DFS");
}
LOG.debug("infoAddr = " + infoAddr);
return infoAddr;
}
/**
* Create a new checkpoint
*/
void doCheckpoint() throws IOException {
// Do the required initialization of the merge work area.
startCheckpoint();
// Tell the namenode to start logging transactions in a new edit file
// Retuns a token that should be used to verify the downloaded image file.
CheckpointSignature sig = (CheckpointSignature)namenode.rollEditLog();
// error simulation code for junit test
if (ErrorSimulator.getErrorSimulation(0)) {
throw new IOException("Simulating error0 " +
"after creating edits.new");
}
downloadCheckpointFiles(sig); // Fetch fsimage and edits
doMerge(sig); // Do the merge
// Upload the new image into the NameNode, providing the new checksum for
// the image file.
putFSImage(sig);
// error simulation code for junit test
if (ErrorSimulator.getErrorSimulation(1)) {
throw new IOException("Simulating error1 " +
"after uploading new image to NameNode");
}
// Then tell the Namenode to make this new uploaded image as the most
// current image.
namenode.rollFsImage();
checkpointImage.endCheckpoint();
LOG.info("Checkpoint done. New Image Size: "
+ checkpointImage.getFsImageName().length());
}
private void startCheckpoint() throws IOException {
checkpointImage.unlockAll();
checkpointImage.getEditLog().close();
checkpointImage.recoverCreate(checkpointDirs, checkpointEditsDirs);
checkpointImage.startCheckpoint();
}
/**
* Merge downloaded image and edits and write the new image into
* current storage directory.
*/
private void doMerge(CheckpointSignature sig) throws IOException {
FSNamesystem namesystem =
new FSNamesystem(checkpointImage, conf);
assert namesystem.dir.fsImage == checkpointImage;
checkpointImage.doMerge(sig);
}
/**
* @param argv The parameters passed to this program.
* @exception Exception if the filesystem does not exist.
* @return 0 on success, non zero on error.
*/
private int processArgs(String[] argv) throws Exception {
if (argv.length < 1) {
printUsage("");
return -1;
}
int exitCode = -1;
int i = 0;
String cmd = argv[i++];
//
// verify that we have enough command line parameters
//
if ("-geteditsize".equals(cmd)) {
if (argv.length != 1) {
printUsage(cmd);
return exitCode;
}
} else if ("-checkpoint".equals(cmd)) {
if (argv.length != 1 && argv.length != 2) {
printUsage(cmd);
return exitCode;
}
if (argv.length == 2 && !"force".equals(argv[i])) {
printUsage(cmd);
return exitCode;
}
}
exitCode = 0;
try {
if ("-checkpoint".equals(cmd)) {
long size = namenode.getEditLogSize();
if (size >= checkpointSize ||
argv.length == 2 && "force".equals(argv[i])) {
doCheckpoint();
} else {
System.err.println("EditLog size " + size + " bytes is " +
"smaller than configured checkpoint " +
"size " + checkpointSize + " bytes.");
System.err.println("Skipping checkpoint.");
}
} else if ("-geteditsize".equals(cmd)) {
long size = namenode.getEditLogSize();
System.out.println("EditLog size is " + size + " bytes");
} else {
exitCode = -1;
LOG.error(cmd.substring(1) + ": Unknown command");
printUsage("");
}
} catch (RemoteException e) {
//
// This is a error returned by hadoop server. Print
// out the first line of the error mesage, ignore the stack trace.
exitCode = -1;
try {
String[] content;
content = e.getLocalizedMessage().split("\n");
LOG.error(cmd.substring(1) + ": "
+ content[0]);
} catch (Exception ex) {
LOG.error(cmd.substring(1) + ": "
+ ex.getLocalizedMessage());
}
} catch (IOException e) {
//
// IO exception encountered locally.
//
exitCode = -1;
LOG.error(cmd.substring(1) + ": "
+ e.getLocalizedMessage());
} finally {
// Does the RPC connection need to be closed?
}
return exitCode;
}
/**
* Displays format of commands.
* @param cmd The command that is being executed.
*/
private void printUsage(String cmd) {
if ("-geteditsize".equals(cmd)) {
System.err.println("Usage: java SecondaryNameNode"
+ " [-geteditsize]");
} else if ("-checkpoint".equals(cmd)) {
System.err.println("Usage: java SecondaryNameNode"
+ " [-checkpoint [force]]");
} else {
System.err.println("Usage: java SecondaryNameNode " +
"[-checkpoint [force]] " +
"[-geteditsize] ");
}
}
/**
* main() has some simple utility methods.
* @param argv Command line parameters.
* @exception Exception if the filesystem does not exist.
*/
public static void main(String[] argv) throws Exception {
StringUtils.startupShutdownMessage(SecondaryNameNode.class, argv, LOG);
Configuration tconf = new Configuration();
if (argv.length >= 1) {
SecondaryNameNode secondary = new SecondaryNameNode(tconf);
int ret = secondary.processArgs(argv);
System.exit(ret);
}
// Create a never ending deamon
Daemon checkpointThread = new Daemon(new SecondaryNameNode(tconf));
checkpointThread.start();
}
static class CheckpointStorage extends FSImage {
/**
*/
CheckpointStorage() throws IOException {
super();
}
@Override
public
boolean isConversionNeeded(StorageDirectory sd) {
return false;
}
/**
* Analyze checkpoint directories.
* Create directories if they do not exist.
* Recover from an unsuccessful checkpoint is necessary.
*
* @param dataDirs
* @param editsDirs
* @throws IOException
*/
void recoverCreate(Collection<File> dataDirs,
Collection<File> editsDirs) throws IOException {
Collection<File> tempDataDirs = new ArrayList<File>(dataDirs);
Collection<File> tempEditsDirs = new ArrayList<File>(editsDirs);
this.storageDirs = new ArrayList<StorageDirectory>();
setStorageDirectories(tempDataDirs, tempEditsDirs);
for (Iterator<StorageDirectory> it =
dirIterator(); it.hasNext();) {
StorageDirectory sd = it.next();
boolean isAccessible = true;
try { // create directories if don't exist yet
if(!sd.getRoot().mkdirs()) {
// do nothing, directory is already created
}
} catch(SecurityException se) {
isAccessible = false;
}
if(!isAccessible)
throw new InconsistentFSStateException(sd.getRoot(),
"cannot access checkpoint directory.");
StorageState curState;
try {
curState = sd.analyzeStorage(HdfsConstants.StartupOption.REGULAR);
// sd is locked but not opened
switch(curState) {
case NON_EXISTENT:
// fail if any of the configured checkpoint dirs are inaccessible
throw new InconsistentFSStateException(sd.getRoot(),
"checkpoint directory does not exist or is not accessible.");
case NOT_FORMATTED:
break; // it's ok since initially there is no current and VERSION
case NORMAL:
break;
default: // recovery is possible
sd.doRecover(curState);
}
} catch (IOException ioe) {
sd.unlock();
throw ioe;
}
}
}
/**
* Prepare directories for a new checkpoint.
* <p>
* Rename <code>current</code> to <code>lastcheckpoint.tmp</code>
* and recreate <code>current</code>.
* @throws IOException
*/
void startCheckpoint() throws IOException {
for(StorageDirectory sd : storageDirs) {
moveCurrent(sd);
}
}
void endCheckpoint() throws IOException {
for(StorageDirectory sd : storageDirs) {
moveLastCheckpoint(sd);
}
}
/**
* Merge image and edits, and verify consistency with the signature.
*/
private void doMerge(CheckpointSignature sig) throws IOException {
getEditLog().open();
StorageDirectory sdName = null;
StorageDirectory sdEdits = null;
Iterator<StorageDirectory> it = null;
it = dirIterator(NameNodeDirType.IMAGE);
if (it.hasNext())
sdName = it.next();
it = dirIterator(NameNodeDirType.EDITS);
if (it.hasNext())
sdEdits = it.next();
if ((sdName == null) || (sdEdits == null))
throw new IOException("Could not locate checkpoint directories");
loadFSImage(FSImage.getImageFile(sdName, NameNodeFile.IMAGE));
loadFSEdits(sdEdits, null);
sig.validateStorageInfo(this);
saveNamespace(false);
}
}
}