[HDFS-6926] DN support for saving replicas to persistent storage and evicting in-memory replicas

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: HDFS-6581
• Fix Version/s: 2.6.0
• Component/s: datanode
• Hadoop Flags: Reviewed
• Assignee: Arpit Agarwal
• Reporter: Arpit Agarwal
• Created: 23/Aug/14 20:29
• Updated: 01/Dec/14 03:09
• Resolved: 27/Aug/14 22:52

Description

Add the following:

1. A lazy writer on the DN to move replicas from RAM disk to persistent storage.
2. 'Evict' persisted replicas from RAM disk to make space for new blocks.