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From "Jean-Daniel Cryans (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-4089) blockCache contents report
Date Mon, 01 Aug 2011 18:04:09 GMT

    [ https://issues.apache.org/jira/browse/HBASE-4089?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13073635#comment-13073635

Jean-Daniel Cryans commented on HBASE-4089:

Nice document Doug, it puts everyone else to shame :)

I don't think we can expose those metrics through JMX/Ganglia/OpenTSDB as they will be changing
a lot. It would be "doable" only if the regions and families never changed IMO. I'd prefer
we concentrate on presenting this information from inside HBase.

In the nice to haves I'd like to see:

 - Number of accesses/misses per block or family (could see what's hot, well cached, etc)
 - Total size of the family on disk (then you can tell what portion of the dataset you cached)

Regarding the Writable question, you have to do that because it's required by Hadoop RPC.
Since you are adding new infos, you'll have to implement it. Don't forget the default constructor!

For the web UI, what about making the region name clickable?

> blockCache contents report
> --------------------------
>                 Key: HBASE-4089
>                 URL: https://issues.apache.org/jira/browse/HBASE-4089
>             Project: HBase
>          Issue Type: New Feature
>            Reporter: Doug Meil
>         Attachments: hbase_4089_blockcachereport.pdf
> Summarized block-cache report for a RegionServer would be helpful.  For example ...
> table1
>   cf1   100 blocks, totalBytes=yyyyy, averageTimeInCache=XXXX hours
>   cf2   200 blocks, totalBytes=zzzzz, averageTimeInCache=XXXX hours
> table2
>   cf1  75 blocks, totalBytes=yyyyy, averageTimeInCache=XXXX hours
>   cf2 150 blocks, totalBytes=zzzzz, averageTimeInCache=XXXX hours
> ... Etc.
> The current metrics list blockCacheSize and blockCacheFree, but there is no way to know
what's in there.  Any single block isn't really important, but the patterns of what CF/Table
they came from, how big are they, and how long (on average) they've been in the cache, are
> No such interface exists in HRegionInterface.  But I think it would be helpful from an
operational perspective.
> Updated (7-29):  Removing suggestion for UI.  I would be happy just to get this report
on a configured interval dumped to a log file.

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