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https://issues.apache.org/jira/browse/HADOOP-227?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12462313
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Milind Bhandarkar commented on HADOOP-227:
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Comments on Periodic Checkpointing Patch - v2
----------------------------------------
fs.checkpoint.period should be in seconds, not milliseconds.
Code still contains debugging printfs. Log messages are not descriptive
enough.
TransferFsImage.java has windows-style crlf line-endings.
TestCheckpoint does not test periodic checkpointing. Instead it does the
same thing as TestRestartDFS.
Newly added methods in namesystem should not be public.
FSImage.java has several whitespace-only-changes.
In FSEditLog.java, getEditLogSize checks to see if all edit logs have the same
length. However, this may not be true. If one of the local or remote fs which
stores edits is full (or has exceeded quotas), the edits log will be of
different sizes. In that case getEditLogSize should return maximum
among all edits.
SecondaryNamenode.java does not use Logging to print errors, instead
uses System.err.
printUsage is called once with an empty string.
printUsage prints [report] instead of [-geteditsize].
It should be possible to run the checkpointer as a cron job. There is
no option for the secondaryNamenode to exit after finishing checkpointing.
default masters files is not added. It should contain localhost.
hadoop-daemons.sh usage contains [--file configfile]. It should be
called [--hosts hostlistfile].
> Namespace check pointing is not performed until the namenode restarts.
> ----------------------------------------------------------------------
>
> Key: HADOOP-227
> URL: https://issues.apache.org/jira/browse/HADOOP-227
> Project: Hadoop
> Issue Type: Bug
> Components: dfs
> Affects Versions: 0.2.0
> Reporter: Konstantin Shvachko
> Assigned To: dhruba borthakur
> Attachments: patch-async-checkpoints-0.9.0,
> patch-async-checkpoints-0.9.0, patch-async-checkpoints-0.9.0,
> periodiccheckpoint.patch, periodiccheckpoint2.patch
>
>
> In current implementation when the name node starts, it reads its image file,
> then
> the edits file, and then saves the updated image back into the image file.
> The image file is never updated after that.
> In order to provide the system reliability reliability the namespace
> information should
> be check pointed periodically, and the edits file should be kept relatively
> small.
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