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From aaron morton <aa...@thelastpickle.com>
Subject Re: Any experience of 20 node mini-itx cassandra cluster
Date Sun, 14 Apr 2013 18:39:16 GMT
That's better. 

The SSD size is a bit small, and be warned that you will want to leave 50Gb to 100GB free
to allow room for compaction (using the default size tiered). 

On the ram side you will want to run about 4GB (assuming cass 1.2) for the JVM the rest can
be off heap Cassandra structures. This may not leave too much free space for the os page cache,
but SSD may help there.

Cheers
  
-----------------
Aaron Morton
Freelance Cassandra Consultant
New Zealand

@aaronmorton
http://www.thelastpickle.com

On 13/04/2013, at 4:47 PM, Jabbar Azam <ajazam@gmail.com> wrote:

> What about using quad core athlon x4 740 3.2 GHz with 8gb of ram and 256gb ssds?
> 
> I know it will depend on our workload but will be better than a dual core CPU. I think....
> 
> Jabbar Azam
> 
> On 13 Apr 2013 01:05, "Edward Capriolo" <edlinuxguru@gmail.com> wrote:
> Duel core not the greatest you might run into GC issues before you run out of IO from
your ssd devices. Also cassandra has other concurrency settings that are tuned roughly around
the number of processors/cores. It is not uncommon to see 4-6 cores of cpu (600 % in top dealing
with young gen garbage managing lots of sockets whatever.
> 
> 
> On Fri, Apr 12, 2013 at 12:02 PM, Jabbar Azam <ajazam@gmail.com> wrote:
> That's my guess. My colleague is still looking at CPU's so I'm hoping he can get quad
core CPU's for the servers.
> 
> Thanks
> 
> Jabbar Azam
> 
> 
> On 12 April 2013 16:48, Colin Blower <cblower@barracuda.com> wrote:
> If you have not seen it already, checkout the Netflix blog post on their performance
testing of AWS SSD instances.
> 
> http://techblog.netflix.com/2012/07/benchmarking-high-performance-io-with.html
> 
> My guess, based on very little experience, is that you will be CPU bound.
> 
> 
> On 04/12/2013 03:05 AM, Jabbar Azam wrote:
>> Hello,
>> 
>> I'm going to be building a 20 node cassandra cluster in one datacentre. The spec
of the servers will roughly be dual core Celeron CPU, 256 GB SSD, 16GB RAM and two nics.
>> 
>> 
>> Has anybody done any performance testing with this setup or have any gotcha's I should
be aware of wrt to the hardware?
>> 
>>  I do realise the CPU is fairly low computational power but I'm going to assume the
system is going to be IO bound hence the RAM and SSD's.
>> 
>> 
>> Thanks
>> 
>> Jabbar Azam
> 
> 
> -- 
> Colin Blower
> Software Engineer
> Barracuda Networks Inc.
> +1 408-342-5576 (o)
> 
> 


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