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https://issues.apache.org/jira/browse/HDFS-5320?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13800319#comment-13800319
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Colin Patrick McCabe commented on HDFS-5320:
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You may be able to start the caching process, but then fail to complete it. It
seems like with this patch, {{numBlocksFailedToCache}} would not be incremented
in this case. Why not put the metric inside {{FsDatasetCache}} itself? That
way, if the caching task failed to complete, it could simply increment the
enclosing statistic.
This might be a dumb question, but do we have to do anything special to get a
"moving window" view of this exposed to clients? Really what they're
interested in is number of caching failures in the last 5 minutes, 50 minutes,
5 days, etc. It would be nice to make sure we're giving clients what they need
in that regard.
> Add datanode caching metrics
> ----------------------------
>
> Key: HDFS-5320
> URL: https://issues.apache.org/jira/browse/HDFS-5320
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: datanode
> Affects Versions: HDFS-4949
> Reporter: Andrew Wang
> Assignee: Andrew Wang
> Priority: Minor
> Attachments: hdfs-5320-1.patch, hdfs-5320-2.patch
>
>
> It'd be good to hook up datanode metrics for # (blocks/bytes)
> (cached/uncached/failed to cache) over different time windows
> (eternity/1hr/10min/1min).
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