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From "Kevin O'dell" <kevin.od...@cloudera.com>
Subject Re: Region is out of bounds
Date Wed, 03 Dec 2014 14:38:06 GMT
Vladimir,

  I know you said, "do not ask me why", but I am going to have to ask you
why.  The fact you are doing this(this being blocking store files > 200)
tells me there is something or multiple somethings wrong with your cluster
setup.  A couple things come to mind:

* During this heavy write period, could we use bulk loads?  If so, this
should solve almost all of your problems

* 1GB region size is WAY too small, and if you are pushing the volume of
data you are talking about I would recommend 10 - 20GB region sizes this
should help keep your region count smaller as well which will result in
more optimal writes

* Your cluster may be undersized, if you are setting the blocking to be
that high, you may be pushing too much data for your cluster overall.

Would you be so kind as to pass me a few pieces of information?

1.) Cluster size
2.) Average region count per RS
3.) Heap size, Memstore global settings, and block cache settings
4.) a RS log to pastebin and a time frame of "high writes"

I can probably make some solid suggestions for you based on the above data.

On Wed, Dec 3, 2014 at 1:04 AM, Vladimir Rodionov <vladrodionov@gmail.com>
wrote:

> This is what we observed in our environment(s)
>
> The issue exists in CDH4.5, 5.1, HDP2.1, Mapr4
>
> If some one sets # of blocking stores way above default value, say - 200 to
> avoid write stalls during intensive data loading (do not ask me , why we do
> this), then
> one of the regions grows indefinitely and takes more 99% of overall table.
>
> It can't be split because it still has orphaned reference files. Some of a
> reference files are able to avoid compactions for a long time, obviously.
>
> The split policy is IncreasingToUpperBound, max region size is 1G. I do my
> tests on CDH4.5 mostly but all other distros seem have the same issue.
>
> My attempt to add reference files forcefully to compaction list in
> Store.requetsCompaction() when region exceeds recommended maximum size did
> not work out well - some weird results in our test cases (but HBase tests
> are OK: small, medium and large).
>
> What is so special with these reference files? Any ideas, what can be done
> here to fix the issue?
>
> -Vladimir Rodionov
>



-- 
Kevin O'Dell
Systems Engineer, Cloudera

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