I found a patch in https://issues.apache.org/jira/browse/HDFS-7097   The author says : “Since block reports are not modifying any state that is being saved to fsimage, I propose letting them through during checkpointing.”   block reports will change block map, this will save in fsimage also.   why do not need lock block reports? how fsimage , edit log and block reports combin to a file? ... View more