[HDFS-5889] When rolling upgrade is in progress, standby NN should create checkpoint for downgrade.

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: HDFS-5535 (Rolling upgrades)
• Component/s: namenode
• Hadoop Flags: Reviewed
• Assignee: Tsz-wo Sze
• Reporter: Tsz-wo Sze
• Created: 05/Feb/14 07:54
• Updated: 18/Feb/14 20:47
• Resolved: 13/Feb/14 08:05

Description

After rolling upgrade is started and checkpoint is disabled, the edit log may grow to a huge size. It is not a problem if rolling upgrade is finalized normally since NN keeps the current state in memory and it writes a new checkpoint during finalize. However, it is a problem if admin decides to downgrade. It could take a long time to apply edit log. Rollback does not have such problem.