[HADOOP-3328] DFS write pipeline : only the last datanode needs to verify checksum

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.16.0
• Fix Version/s: 0.19.0
• Hadoop Flags: Reviewed
• Assignee: Raghu Angadi
• Reporter: Raghu Angadi
• Created: 30/Apr/08 18:39
• Updated: 08/Jul/09 16:43
• Resolved: 09/Jul/08 17:47

Description

Currently all the datanodes in DFS write pipeline verify checksum. Since the current protocol includes acks from the datanodes, an ack from the last node could also serve as verification that checksum ok. In that sense, only the last datanode needs to verify checksum. Based on this comment from HADOOP-1702, CPU consumption might go down by another 25-30% (4/14) after HADOOP-1702.

Also this would make it easier to use transferTo() and transferFrom() on intermediate datanodes since they don't need to look at the data.