We reached a significant milestone in HDFS: the Namenode HA branch was merged into the trunk. With this merge, HDFS trunk now supports HOT failover.
Significant enhancements were completed to make HOT Failover work:
- Configuration changes for HA
- Notion of active and standby states were added to the Namenode
- Client-side redirection
- Standby processing journal from Active
- Dual block reports to Active and Standby
We have extensively tested HOT manual failover in our labs over the last few months. The HDFS team is now working on completing automatic failover. Please see HDFS-1623 for more details.