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From Jonathan Ellis <>
Subject Re: Cassandra performance decreases drastically with increase in data size.
Date Thu, 30 May 2013 05:05:52 GMT
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:

On Wed, May 29, 2013 at 11:32 PM, srmore <> 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
> 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

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