This scenario is applicable in NN and BNN case.
When the namenode goes down after creating the edits.new, on subsequent restart the divertFileStreams will not happen to edits.new as the edits.new file is already present and the size is zero.
so on trying to saveCheckPoint an exception occurs
2011-05-23 16:38:57,476 WARN org.mortbay.log: /getimage: java.io.IOException: GetImage failed. java.io.IOException: Namenode has an edit log with timestamp of 2011-05-23 16:38:56 but new checkpoint was created using editlog with timestamp 2011-05-23 16:37:30. Checkpoint Aborted.
This is a bug or is that the behaviour.