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From Asaf Mesika <asaf.mes...@gmail.com>
Subject Re: Slow random reads, SocketTimeoutExceptions
Date Wed, 11 Jul 2012 20:22:45 GMT
What's your cell value size?
What do you mean by 100 tables in one column family?
Can you please specify what was your insert rate and how many nodes you

Sent from my iPhone

On 11 ביול 2012, at 22:08, Adrien Mogenet <adrien.mogenet@gmail.com> wrote:

Hi there,

I'm discovering HBase and comparing it with other distributed database I
know much better. I am currently stressing my testing platform (servers
with 32 GB Ram, 16 GB allocated to HBase JVM) and I'm observing strange
performances... I'm putting tons of well-spred data (100 Tables of 100M
rows in a single column family) and then I'm performing random reads. I get
good read performances while the table does not have too much data in it,
but in a big table, I only get around 100/300 qps. I'm not swapping, don't
see any long pauses due to GC and insert rate is still very high, but
nothing come from reads and it often results in a SocketTimeoutException
(while waiting for channel to be ready for read exceptions, etc.).

I noticed that certain StoreFile were very big (~120 GB) and I adjusted
compaction strategy to no compact such big files (I don't know if it can be
related to my issue).

I noticed that when I'm stressing my cluster with Get requests, everything
*looks* fine until a RegionServer does not yield a data locally and fetch
it from HDFS, resulting in high and long network use, more than 60 seconds,
that's throwing SocketTimeoutException).

How does HBase handle data locality for random accesses ? Could it be a
lead to solve this kind of issue ?
My block cache of 5 GB is not full at all...

Adrien Mogenet

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