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https://issues.apache.org/jira/browse/HDFS-13818?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16630373#comment-16630373
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Adam Antal commented on HDFS-13818:
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I admit luring might happens, though it has been emphasized both in the command
line and the Hadoop Guide (Image Viewer markdown file) that the search is not
exhaustive. We can discuss a better name of the command / what could not cause
confusion to the users.
Indeed, if one wants to convince himself to the fsimage is not corrupted in any
way, the best is to pick a NN and load the image. Aside from that, it still has
several advantages compared to the full NN checking, so I believe the new
processor fits well for other purposes.
> Extend OIV to detect FSImage corruption
> ---------------------------------------
>
> Key: HDFS-13818
> URL: https://issues.apache.org/jira/browse/HDFS-13818
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: hdfs
> Reporter: Adam Antal
> Assignee: Adam Antal
> Priority: Major
> Attachments: HDFS-13818.001.patch, HDFS-13818.002.patch,
> HDFS-13818.003.patch, HDFS-13818.003.patch, HDFS-13818.004.patch,
> HDFS-13818.005.patch, HDFS-13818.006.patch,
> OIV_CorruptionDetector_processor.001.pdf,
> OIV_CorruptionDetector_processor.002.pdf
>
>
> A follow-up Jira for HDFS-13031: an improvement of the OIV is suggested for
> detecting corruptions like HDFS-13101 in an offline way.
> The reasoning is the following. Apart from a NN startup throwing the error,
> there is nothing in the customer's hand that could reassure him/her that the
> FSImages is good or corrupted.
> Although real full checking of the FSImage is only possible by the NN, for
> stack traces associated with the observed corruption cases the solution of
> putting up a tertiary NN is a little bit of overkill. The OIV would be a
> handy choice, already having functionality like loading the fsimage and
> constructing the folder structure, we just have to add the option of
> detecting the null INodes. For e.g. the Delimited OIV processor can already
> use in disk MetadataMap, which reduces memory consumption. Also there may be
> a window for parallelizing: iterating through INodes for e.g. could be done
> distributed, increasing efficiency, and we wouldn't need a high mem-high CPU
> setup for just checking the FSImage.
> The suggestion is to add a --detectCorruption option to the OIV which would
> check the FSImage for consistency.
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