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From Jean-Daniel Cryans <jdcry...@apache.org>
Subject Re: randomWrite tests gives random results
Date Mon, 06 Feb 2012 19:02:06 GMT
If you didn't configure anything more than the heap, PE will by
default create a table with 1 region and a low (albeit default)
memstore size. This means it's spending its time waiting on splits and
it's recompacting your data all the time which wastes a lot of iops.

You didn't tell use which version you're using so here's two things to
fix the former:

 0.90: run the import a few times so that the regions can split, then
run a major compaction.
 0.92: use https://issues.apache.org/jira/browse/HBASE-4440, it's
pretty easy to backport.

To fix the latter, set MEMSTORE_SIZE to something better like 256MB
and also once the table is pre-splitted change the MAX_FILESIZE to


On Mon, Feb 6, 2012 at 7:15 AM, Assarsson, Emil
<Emil.Assarsson@sonyericsson.com> wrote:
> Hi,
> I'm tryng to optimize a hbase cluster (on hdfs) with the test randomWrite. I have 7 nodes:
1 zookeeper/name/hbase-master/jobtracker and 6 region/data/tasktrackers. Each with 1 disk,
16G memory, 2 x 4 cores. I know that I really should have more disks but for the time being
I'm trying to do the best with what I have.
> I have configured tasktrackers to run 1 map/1 red on each host.
> The problem I'm seeing is that I get very varying results spanning from 16sec/100000inserts
to 240sec/100000inserts.
> Currently I'm using a 10G heapsize on hbase and 3G heapsize on hdfs.
> How do I find out what makes it this random? I think I should be able to get around 22sec/100000inserts.
> Best regards
> Emil Assarsson
> Sony Ericsson Mobile Communications AB
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