On Tue, Feb 14, 2006 at 02:42:21PM -0800, Harry Mangalam wrote:
> We are building a small test cluster (5 nodes of 2x2dual-core opterons) for 
> doing some parallel file system research (probably mostly with pvfs2) and I'm 
> trying to gather info on a cost/time optimal setup.  The cluster will also be 
> used for computation in atmospheric data reduction of fairly large files 
> (hence the interest in using a pfs).  Most of the applications will be using 
> MPI-IO at some level (HDF5's parallel access, parallel netCDF).
> It seems that more nodes will be better for I/O up to the point of saturation 
> of the backplane and/or interconnect.
> 
> For the interconnect technology, the lower-latency technologies such as 
> myrinet and IB are preferred, but is it possible to bond ethernets (initially 
> 1GE, then later 10GE) to provide better thruput?  Is it advisable to try this 
> or will the latency end up killing such an effort anyway?

If you channel bond you'll be looking at a max bandwidth of what, 200
MBytes/sec?  You'll be hard-pressed to get that much disk performance,
so you'll end up with a very unbalanced (network-heavy) solution.
Unless you've got some high-end raid hardware on each server node,
you'll only come close to 200 MBytes/sec if you consitently work from
the cache.  Possible, depending on your datatset.

> Is there a downside to having IB on the motherboards anyway (besides the 
> cost)?

I know nothing about IB hardware...

==rob

-- 
Rob Latham
Mathematics and Computer Science Division    A215 0178 EA2D B059 8CDF
Argonne National Labs, IL USA                B29D F333 664A 4280 315B
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