[Users] BenchIO_HDF5 questions

[Erik Schnetter]

On Apr 18, 2008, at 08:12:16, Avi Purkayastha wrote:

> Hello,
> I have been testing the BenchIO_HDF5 benchmark and a number of  
> issues came up:
>
> 1) I was testing on a 10 GB filesystem and seem to run out of space  
> on runs with varying proc counts. The benchmark page lists that each  
> proc contributes 352 MB to the overall data checkpoint, so does that  
> mean that the total required disk space is N*352 MB, where N is the  
> number of procs?

Yes, this is correct.  This corresponds to a weak scaling test where  
the problem size grows with the number of available processors.  This  
test emulates writing a checkpoint file where each processor writes  
out the complete state information to disk.

> 2) Is there an order of preference based on importance, for these  
> three tests -- onefile, eachproc, and 8proc from the Cactus user  
> community, or all of equal importance?

I would order them in order of decreasing importance as 8proc,  
eachproc, and then with a large distance onefile.  We don't use  
onefile any more for production runs on large numbers of processors.

> 3) Is there any data from these I/O tests listed anywhere from  
> different architecture systems with fast disks and/or filesystems,  
> so one can get a sense of what is considered good, bad or ugly IO  
> rates?


I'm not aware of any.  We have had concentrated benchmarking efforts  
for CPU power, but not for disk I/O.  I could be wrong.

-erik

-- 
Erik Schnetter <schnetter at cct.lsu.edu>   http://www.cct.lsu.edu/~eschnett/

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