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https://issues.apache.org/jira/browse/HADOOP-1978?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Konstantin Shvachko updated HADOOP-1978:
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Attachment: editsNew-0-15.patch
- I fixed the problem as described above by making edits.new empty at the same
time the edits gets emptied.
- I truncate edits files when they are emptied, otherwise it is not clear what
is the real file size.
- Based on that modified TestCheckpoint, which now checks edits and image files
existence and lengths.
The test fails with the old code and succeeds with the new.
- Cleaned up EditLogOutputStream: it calls force() now on the FileChannel
instead of flush() and synch().
This makes the fd member obsolete. I removed it.
- Fsck was failing consistently on my machine because safe-mode was still on
when the test was trying
to delete files. It should call waitActive() before deleting.
- Patch for 0.14 is coming soon.
- For hadoop 0.13 in order to avoid this problem one should just start the
cluster with -upgrade. Then edits.new
will be merged with the image as well as the edits, but will not be renamed to
edits, since it does not
exist in the new image directory.
> Name-node should remove edits.new during startup rather than renaming it to
> edits.
> ----------------------------------------------------------------------------------
>
> Key: HADOOP-1978
> URL: https://issues.apache.org/jira/browse/HADOOP-1978
> Project: Hadoop
> Issue Type: Bug
> Components: dfs
> Affects Versions: 0.13.1
> Reporter: Konstantin Shvachko
> Assignee: Konstantin Shvachko
> Priority: Blocker
> Fix For: 0.14.2, 0.15.0
>
> Attachments: editsNew-0-15.patch
>
>
> Secondary name-node fails in the middle. The main name-node writes its
> journal transactions into edits.new at that time.
> If the name-node is shut down after that and restarted, then loadFSImage()
> reads current image file, merges it with the edits
> file and with the edits.new file.
> Now saveFSImage() saves new image file, creates empty edits file, and then
> calls rollFSImage(), which particularly renames
> edits.new into edits. This is a mistake, during startup edits.new should be
> merely removed after merging it with the image.
> The purpose of calling rollFSImage() during startups imho is to recover from
> an unsuccessful checkpoint. So an easy fix
> is to empty edits.new before calling rollFSImage the same as edits are
> emptied, then rollFSImage will rename empty file
> to empty which gives us the desired result.
> We should fix this bug both in 0.14 and 0.15. I make it a blocker for 0.15.
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