/// <exception cref="System.IO.IOException"/>
public override long GetJournalCTime()
{
StorageInfo sInfo = new StorageInfo((HdfsServerConstants.NodeType)null);
sInfo.ReadProperties(sd);
return(sInfo.GetCTime());
}
/// <summary>
/// Return true if this storage dir can roll back to the previous storage
/// state, false otherwise.
/// </summary>
/// <remarks>
/// Return true if this storage dir can roll back to the previous storage
/// state, false otherwise. The NN will refuse to run the rollback operation
/// unless at least one JM or fsimage storage directory can roll back.
/// </remarks>
/// <param name="storage">the storage info for the current state</param>
/// <param name="prevStorage">the storage info for the previous (unupgraded) state</param>
/// <param name="targetLayoutVersion">the layout version we intend to roll back to</param>
/// <returns>true if this JM can roll back, false otherwise.</returns>
/// <exception cref="System.IO.IOException">in the event of error</exception>
internal static bool CanRollBack(Storage.StorageDirectory sd, StorageInfo storage
, StorageInfo prevStorage, int targetLayoutVersion)
{
FilePath prevDir = sd.GetPreviousDir();
if (!prevDir.Exists())
{
// use current directory then
Log.Info("Storage directory " + sd.GetRoot() + " does not contain previous fs state."
);
// read and verify consistency with other directories
storage.ReadProperties(sd);
return(false);
}
// read and verify consistency of the prev dir
prevStorage.ReadPreviousVersionProperties(sd);
if (prevStorage.GetLayoutVersion() != targetLayoutVersion)
{
throw new IOException("Cannot rollback to storage version " + prevStorage.GetLayoutVersion
() + " using this version of the NameNode, which uses storage version " + targetLayoutVersion
+ ". " + "Please use the previous version of HDFS to perform the rollback.");
}
return(true);
}