Cassandra on heterogeneous servers

[Daniel Bruegge <da...@googlemail.com>]

Hi,

I am currently running 4 cassandra nodes with the following hardware

- AMD Athlon 64 X2 6000+
- 8G RAM
- 750G hard disk

It shows not such a good writing performance and a really bad read
performance with sometimes also timeouts. I was wondering if it makes
sense to add 2 nodes with a different hardware (8 CPUs and more RAM)
to improve this. Or does a cassandra cluster works best with the same
hardware in every node?

Thanks & best regards

Daniel

Re: Cassandra on heterogeneous servers

[aaron morton <aa...@thelastpickle.com>]

> Or does a cassandra cluster works best with the same
> hardware in every node?
Things work best if the nodes all have the same HW. If you mix HW then you need to capacity plan against a machine made up of all of the lowest performing parts. 

What's happening with the poor performance ? 

Poke around with http://spyced.blogspot.com/2010/01/linux-performance-basics.html
See what's happening with nodetool tpstats ?
What sort of load are the nodes under ? How much data, how much throughout ? 
Have you changed any of the default setting ? 

I would guess with a single physical spindle you may have an IO bottleneck.

Hope that helps. 

-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com

On 10/01/2012, at 3:42 AM, Daniel Bruegge wrote:

> Hi,
> 
> I am currently running 4 cassandra nodes with the following hardware
> 
> - AMD Athlon 64 X2 6000+
> - 8G RAM
> - 750G hard disk
> 
> It shows not such a good writing performance and a really bad read
> performance with sometimes also timeouts. I was wondering if it makes
> sense to add 2 nodes with a different hardware (8 CPUs and more RAM)
> to improve this. Or does a cassandra cluster works best with the same
> hardware in every node?
> 
> Thanks & best regards
> 
> Daniel