hbase-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Varun Sharma (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-8370) Report data block cache hit rates apart from aggregate cache hit rates
Date Wed, 26 Jun 2013 22:08:20 GMT

    [ https://issues.apache.org/jira/browse/HBASE-8370?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13694296#comment-13694296
] 

Varun Sharma commented on HBASE-8370:
-------------------------------------

So, it seems that we have per block type metrics from SchemaMetrics under the region server
and they are exposed as /jmx.

The question is, which metric should we report on the region server UI. Right now all our
clusters 99 % cache hit ratio which is false, since 20 % percent of the time there is a DataBlock
miss and we are hitting disk for 20 % of requests.

I have been misled by this number in the past, and I think there could be others, who are
being similarly misled. So, should we just report another more representative metric on the
region server console.

Varun
                
> Report data block cache hit rates apart from aggregate cache hit rates
> ----------------------------------------------------------------------
>
>                 Key: HBASE-8370
>                 URL: https://issues.apache.org/jira/browse/HBASE-8370
>             Project: HBase
>          Issue Type: Improvement
>          Components: metrics
>            Reporter: Varun Sharma
>            Assignee: Varun Sharma
>            Priority: Minor
>
> Attaching from mail to dev@hbase.apache.org
> I am wondering whether the HBase cachingHitRatio metrics that the region server UI shows,
can get me a break down by data blocks. I always see this number to be very high and that
could be exagerated by the fact that each lookup hits the index blocks and bloom filter blocks
in the block cache before retrieving the data block. This could be artificially bloating up
the cache hit ratio.
> Assuming the above is correct, do we already have a cache hit ratio for data blocks alone
which is more obscure ? If not, my sense is that it would be pretty valuable to add one.

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira

Mime
View raw message