[HDFS-1489] breaking the dependency between FSEditLog and FSImage

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Incomplete
• Affects Version/s: 0.21.0
• Component/s: namenode
• Assignee: Ivan Kelly
• Reporter: Diego Marron
• Created: 05/Nov/10 18:30
• Updated: 04/Mar/11 12:06
• Resolved: 04/Mar/11 12:06

Description

This is a refactor patch which its main concerns are:

• breaking the dependency between FSEditLog and FSImage
• Splitting the abstracting the error handling and directory management,
• Decoupling Storage from FSImage.

In order to accomplish the above goal, we will need to introduce new classes:

• NNStorage: Will care about the storage. It extends Storage class, and will contain the StorageDirectories.
• NNUtils: Some utility static methods on FSImage and FSEditLog will be moved here.
• PersistenceManager: FSNameSystem will now be responsible for managing the FSImage & FSEditLog objects. There will be some logic that will have to moved out of FSImage to facilite this. For this we propose a PersistanceManager? object as follows.

For more deep details, see the design document uploaded.

Issue Links

• relates to: HDFS-1473 Refactor storage management into separate classes than fsimage file reading/writing
• relates to: HDFS-1506 Refactor fsimage loading code

Sub-Tasks

• Separate Storage from FSImage: Resolved