[HDFS-5076] Add MXBean methods to query NN's transaction information and JournalNode's journal status

• Type: New Feature
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 3.0.0-alpha1
• Fix Version/s: 2.1.1-beta
• Hadoop Flags: Reviewed
• Assignee: Jing Zhao
• Reporter: Jing Zhao
• Created: 07/Aug/13 20:07
• Updated: 12/May/16 18:17
• Resolved: 15/Aug/13 18:48

Description

Currently NameNode already provides RPC calls to get its last applied transaction ID and most recent checkpoint's transaction ID. It can be helpful to provide support to enable querying these information through JMX, so that administrators and applications like Ambari can easily decide if a forced checkpoint by calling saveNamespace is necessary. Similarly we can add MxBean interface for JournalNodes to query the status of journals (e.g., whether journals are formatted or not).