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From Bryan Talbot <btal...@aeriagames.com>
Subject Re: Cassandra performance decreases drastically with increase in data size.
Date Fri, 31 May 2013 03:48:43 GMT
One or more of these might be effective depending on your particular usage

- remove data (rows especially)
- add nodes
- add ram (has limitations)
- reduce bloom filter space used by increasing fp chance
- reduce row and key cache sizes
- increase index sample ratio
- reduce compaction concurrency and throughput
- upgrade to cassandra 1.2 which does some of these things for you


-Bryan



On Thu, May 30, 2013 at 2:31 PM, srmore <comomore@gmail.com> wrote:

> 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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