[HDFS-1972] HA: Datanode fencing mechanism

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: HA branch (HDFS-1623)
• Component/s: datanode, ha, namenode
• Hadoop Flags: Reviewed
• Assignee: Todd Lipcon
• Reporter: Suresh Srinivas
• Created: 20/May/11 16:32
• Updated: 21/Dec/11 12:51
• Resolved: 21/Dec/11 04:32

Description

In high availability setup, with an active and standby namenode, there is a possibility of two namenodes sending commands to the datanode. The datanode must honor commands from only the active namenode and reject the commands from standby, to prevent corruption. This invariant must be complied with during fail over and other states such as split brain. This jira addresses issues related to this, design of the solution and implementation.

Issue Links

• incorporates: HDFS-2627 HA: determine DN's view of which NN is active based on heartbeat responses
• is blocked by: HDFS-2693 Synchronization issues around state transition
• supercedes: HDFS-2603 HA: don't initialize replication queues until entering Active mode