/* * Roll back to old snapshot at the block pool level * If previous directory exists: * <ol> * <li>Rename <SD>/current/<bpid>/current to removed.tmp</li> * <li>Rename * <SD>/current/<bpid>/previous to current</li> * <li>Remove removed.tmp</li> * </ol> * * Do nothing if previous directory does not exist. * @param bpSd Block pool storage directory at <SD>/current/<bpid> */ /// <exception cref="System.IO.IOException"/> internal virtual void DoRollback(Storage.StorageDirectory bpSd, NamespaceInfo nsInfo ) { FilePath prevDir = bpSd.GetPreviousDir(); // regular startup if previous dir does not exist if (!prevDir.Exists()) { return; } // read attributes out of the VERSION file of previous directory Org.Apache.Hadoop.Hdfs.Server.Datanode.BlockPoolSliceStorage prevInfo = new Org.Apache.Hadoop.Hdfs.Server.Datanode.BlockPoolSliceStorage (); prevInfo.ReadPreviousVersionProperties(bpSd); // We allow rollback to a state, which is either consistent with // the namespace state or can be further upgraded to it. // In another word, we can only roll back when ( storedLV >= software LV) // && ( DN.previousCTime <= NN.ctime) if (!(prevInfo.GetLayoutVersion() >= HdfsConstants.DatanodeLayoutVersion && prevInfo .GetCTime() <= nsInfo.GetCTime())) { // cannot rollback throw new InconsistentFSStateException(bpSd.GetRoot(), "Cannot rollback to a newer state.\nDatanode previous state: LV = " + prevInfo.GetLayoutVersion() + " CTime = " + prevInfo.GetCTime() + " is newer than the namespace state: LV = " + HdfsConstants.DatanodeLayoutVersion + " CTime = " + nsInfo.GetCTime()); } Log.Info("Rolling back storage directory " + bpSd.GetRoot() + ".\n target LV = " + nsInfo.GetLayoutVersion() + "; target CTime = " + nsInfo.GetCTime()); FilePath tmpDir = bpSd.GetRemovedTmp(); System.Diagnostics.Debug.Assert(!tmpDir.Exists(), "removed.tmp directory must not exist." ); // 1. rename current to tmp FilePath curDir = bpSd.GetCurrentDir(); System.Diagnostics.Debug.Assert(curDir.Exists(), "Current directory must exist."); Rename(curDir, tmpDir); // 2. rename previous to current Rename(prevDir, curDir); // 3. delete removed.tmp dir DeleteDir(tmpDir); Log.Info("Rollback of " + bpSd.GetRoot() + " is complete"); }
/// <summary>Perform rollback of the storage dir to the previous state.</summary> /// <remarks> /// Perform rollback of the storage dir to the previous state. The existing /// current dir is removed, and the previous dir is renamed to current. /// </remarks> /// <param name="sd">the storage directory to roll back.</param> /// <exception cref="System.IO.IOException">in the event of error</exception> internal static void DoRollBack(Storage.StorageDirectory sd) { FilePath prevDir = sd.GetPreviousDir(); if (!prevDir.Exists()) { return; } FilePath tmpDir = sd.GetRemovedTmp(); Preconditions.CheckState(!tmpDir.Exists(), "removed.tmp directory must not exist for rollback." + "Consider restarting for recovery."); // rename current to tmp FilePath curDir = sd.GetCurrentDir(); Preconditions.CheckState(curDir.Exists(), "Current directory must exist for rollback." ); NNStorage.Rename(curDir, tmpDir); // rename previous to current NNStorage.Rename(prevDir, curDir); // delete tmp dir NNStorage.DeleteDir(tmpDir); Log.Info("Rollback of " + sd.GetRoot() + " is complete."); }