[HDFS-2973] HA: re-enable NO_ACK optimization for block deletion

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: HA branch (HDFS-1623)
• Fix Version/s: HA branch (HDFS-1623)
• Component/s: ha, namenode
• Target Version/s: HA branch (HDFS-1623)
• Hadoop Flags: Reviewed
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 18/Feb/12 01:57
• Updated: 23/Feb/12 12:54
• Resolved: 23/Feb/12 01:25

Description

Currently in trunk, when a file is removed, the deletion request is sent to the DNs with a special NO_ACK flag to indicate that they don't need to ACK the deletion. The NN itself takes care of removing the blocks from the block map, so the deletion report would be redundant.
In the HA branch, we disabled this to fix a failure in TestSafeMode – when the active NN issues a block deletion, and the standby hasn't read the edits yet, this test case expects that it would see the block deletions.
I don't see any actual compelling reasons for this. I think we can restore the optimization and modify the test to pass.

Issue Links

• relates to: HDFS-2692 HA: Bugs related to failover from/into safe-mode