[HDFS-1137] Name node is using the write-ahead log improperly

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Not A Problem
• Component/s: namenode
• Assignee: Unassigned
• Reporter: Benjamin Reed
• Created: 07/May/10 23:50
• Updated: 16/Nov/15 19:48
• Resolved: 30/Jul/14 19:29

Description

The Name node is doing the write-ahead log (WAL) (aka edit log) improperly. Usually when using WAL, changes are written to the log before they are applied to the state. Currently the Namenode does the WAL after applying the change. This means that read may see changes before they are durable. A client may read information and the server fail before the information is written to the WAL, which results in the client reading state that disappears. To fix the Namenode should write changes before (aka ahead of) applying the change.

Issue Links

• is related to: HDFS-8298 HA: NameNode should not shut down completely without quorum, doesn't recover from temporary network outages