[HDFS-2627] HA: determine DN's view of which NN is active based on heartbeat responses

• 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: datanode, ha, namenode
• Target Version/s: HA branch (HDFS-1623)
• Hadoop Flags: Reviewed
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 03/Dec/11 01:25
• Updated: 23/Aug/13 00:28
• Resolved: 08/Dec/11 02:00

Description

This is the first part of the design described in this comment in HDFS-1972. When the DNs start, they should not consider either of the NNs in a block pool to be the active one. Rather, the NNs should include their HA state as part of the heartbeat response to the DN, and the DN will believe whichever NN claims to be active at a higher transaction ID.

Issue Links

• is part of: HDFS-1972 HA: Datanode fencing mechanism
• is related to: HDFS-5014 BPOfferService#processCommandFromActor() synchronization on namenode RPC call delays IBR to Active NN, if Stanby NN is unstable