[gmx-users] apple

[Erik Lindahl]

Hi,
>
> I have 4 dual 2Ghz G5's humming away nicely right now doing gromacs
> benchmarks. On the most apples to apples comparison, the 4 nodes (using
> gigE interconnect) are about the same speed as 8 nodes in our 
> 1.7/1.8Ghz
> xeon cluster, also using gigE. 4 nodes is only a little faster than 2
> nodes because I suspect that the network is already saturated. From the
> beginning we have known that we need more exotic networking, so are
> mostly considering Infiniband.
>
> With the G5's there is, however, an annoying bug. You can only use 1 
> cpu
> per machine on a job.
>

I would say this is a good example :-)

The G5 hardware is great in general, and with the IBM compilers you 
also have good fortran support. However, it is quite common to have 
"strange" bugs like you used to experience with linux 5-6 years ago, 
simply because it is a less mature combination.

Apple are quite aggressive at selling to Universities, and I just got a 
mail from a contact asking if I knew anything about the bug Dean 
describes. I'm sure it will be solved since they are in the business of 
selling clusters now, but it will probably be another year or two 
before it is just as much "plug and play" as linux.

Cheers,

Erik