[HDFS-5074] Allow starting up from an fsimage checkpoint in the middle of a segment

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.1.0-beta, 3.0.0-alpha1
• Fix Version/s: 2.3.0
• Component/s: ha, namenode
• Target Version/s: 2.3.0
• Hadoop Flags: Reviewed
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 06/Aug/13 20:06
• Updated: 12/May/16 18:16
• Resolved: 11/Dec/13 02:02

Description

We've seen the following behavior a couple times:

• SBN is running and somehow encounters an error in the middle of replaying an edit log in the tailer (eg the JN it's reading from crashes)
• SBN successfully has processed half of the edits in the segment it was reading.
• SBN saves a checkpoint, which now falls in the middle of a segment, and then restarts

Upon restart, the SBN will load this checkpoint which falls in the middle of a segment. selectInputStreams then fails when the SBN requests a mid-segment txid.

We should handle this case by downloading the right segment and fast-forwarding to the correct txid.

Issue Links

• relates to: HDFS-5459 fix bootstrapStandby race condition introduced in HDFS-5080
• relates to: HDFS-4128 2NN gets stuck in inconsistent state if edit log replay fails in the middle