[Beowulf] NFS over RDMA performance confusion

Vincent Diepeveen diep at xs4all.nl
Thu Sep 13 05:17:28 PDT 2012


I'm not a database expert,
but are you sure you are using RDMA?

AFAIK mysql just uses TCP/IP which is a lot slower.

On Sep 13, 2012, at 1:52 PM, holway at th.physik.uni-frankfurt.de wrote:

> Hi,
>
> I am a bit confused.
>
> I have 4 top notch dual socket machines with 128GB ram each. I also  
> have a
> Nexenta box which is my NFS / ZFS server. Everything is connected  
> together
> with QDR infiniband.
>
> I want to use this for setup for mysql databases so I am testing  
> for 16K
> random and stride performance.
>
> If I set up a single machine to hammer the fileserver with IOzone I  
> see
> something like 50,000 IOPS but if all four machines are hammering the
> filesystem concurrently we got it up to 180,000 IOPS.
>
> Can anyone tell me what might be the bottleneck on the single  
> machines?
> Why can I not get 180,000 IOPS when running on a single machine.
>
> If I test using IPoIB in connected mode I see this: http:// 
> pastie.org/4708542
>
> Some kind of buffer problem?
>
> Thanks,
>
> Andrew
>
>
>
>
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