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From Gautam Borah <gbo...@appdynamics.com>
Subject impact of using higher Hbase.hregion.memstore.flush.size=512MB
Date Wed, 27 May 2015 20:58:00 GMT
Hi all,

The default size of Hbase.hregion.memstore.flush.size is define as 128 MB .
Could anyone kindly explain what would be the impact if we increase this to
a higher value 512 MB or 800 MB or higher.

We have a very write heavy cluster. Also we run periodic end point co
processor based jobs that operate on the data written in the last 10-15
mins, every 10 minute. We are trying to manage the memstore flush
operations such that the hot data remains in memstore for at least 30-40
mins or longer, so that the job hits disk every 3rd or 4th time it tries to
operate on the hot data (it does scan).

We have region server heap size of 20 GB and set the,

hbase.regionserver.global.memstore.lowerLimit = .45

hbase.regionserver.global.memstore.upperLimit = .55

We observed that if we set the Hbase.hregion.memstore.flush.size=128MB only
10% of the heap is utilized by memstore, after that memstore flushes.

At Hbase.hregion.memstore.flush.size=512MB, we are able to increase the
heap utilization to by memstore to 35%.

It would be very helpful for us to understand the implication of higher
Hbase.hregion.memstore.flush.size  for a long running cluster.



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