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From srmore <comom...@gmail.com>
Subject Re: Cassandra performance decreases drastically with increase in data size.
Date Thu, 30 May 2013 21:31:23 GMT
You are right, it looks like I am doing a lot of GC. Is there any
short-term solution for this other than bumping up the heap ? because, even
if I increase the heap I will run into the same issue. Only the time before
I hit OOM will be lengthened.

It will be while before we go to latest and greatest Cassandra.

Thanks !


On Thu, May 30, 2013 at 12:05 AM, Jonathan Ellis <jbellis@gmail.com> wrote:

> Sounds like you're spending all your time in GC, which you can verify
> by checking what GCInspector and StatusLogger say in the log.
>
> Fix is increase your heap size or upgrade to 1.2:
> http://www.datastax.com/dev/blog/performance-improvements-in-cassandra-1-2
>
> On Wed, May 29, 2013 at 11:32 PM, srmore <comomore@gmail.com> wrote:
> > Hello,
> > I am observing that my performance is drastically decreasing when my data
> > size grows. I have a 3 node cluster with 64 GB of ram and my data size is
> > around 400GB on all the nodes. I also see that when I re-start Cassandra
> the
> > performance goes back to normal and then again starts decreasing after
> some
> > time.
> >
> > Some hunting landed me to this page
> > http://wiki.apache.org/cassandra/LargeDataSetConsiderations which talks
> > about the large data sets and explains that it might be because I am
> going
> > through multiple layers of OS cache, but does not tell me how to tune it.
> >
> > So, my question is, are there any optimizations that I can do to handle
> > these large datatasets ?
> >
> > and why does my performance go back to normal when I restart Cassandra ?
> >
> > Thanks !
>
>
>
> --
> Jonathan Ellis
> Project Chair, Apache Cassandra
> co-founder, http://www.datastax.com
> @spyced
>

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