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From aaron morton <aa...@thelastpickle.com>
Subject Re: Any experience of 20 node mini-itx cassandra cluster
Date Tue, 16 Apr 2013 21:27:43 GMT
> Can't we use LCS? 
Do some reading and some tests…

http://www.datastax.com/dev/blog/leveled-compaction-in-apache-cassandra
http://www.datastax.com/dev/blog/when-to-use-leveled-compaction

Cheers

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

@aaronmorton
http://www.thelastpickle.com

On 15/04/2013, at 10:44 PM, Jabbar Azam <ajazam@gmail.com> wrote:

> I know the SSD's are a bit small but they should be enough for our application. Out test
data is 1.6 TB(including replication of rf=3). Can't we use LCS? This will give us more space
at the expensive of more I/O but SSD's have loads of I/Os.
> 
> 
> 
> 
> 
> Thanks
> 
> Jabbar Azam
> 
> 
> On 14 April 2013 20:20, Jabbar Azam <ajazam@gmail.com> wrote:
> Thanks Aaron.
> 
> Thanks
> 
> Jabbar Azam
> 
> 
> On 14 April 2013 19:39, aaron morton <aaron@thelastpickle.com> wrote:
> 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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