[Beowulf] One network, or two?

[Prentice Bisbal]

Alan Ward wrote:
> 
> Good day.
> 
> I have been reading the ongoing discussion on network usage with some
> interest, mainly because in all (admittedly very small, 4 to 8 node)
> clusters we have set up so far, we have always gone with doubling the
> network. Nowadays we mostly run a 100 MBit/s "el cheapo" FastEthernet
> for control, NFS and monitoring, while the faster Gigabit is exclusively
> for MPI. Applications are CFD, with various levels of granularity.
> 
> Anybody care to comment?
> 
> -Alan

My new cluster, which is still in labor, will have InfiniBand for MPI,
and we have 10 Gb ethernet switches for management/NFS, etc. The nodes
only have 1 Gb ethernet, so it will be effectively a 1 Gb network.

I'm also curious as to whether the dual networks are overkill, and if
using a slower network for I/O will cause the system to be slower than
doing all traffic over IB, since I/O will be slower and cause the nodes
to wait longer for these ops to finish.

-- 
Prentice