[Users] BenchIO_HDF5 questions

[Thomas Radke]

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.

> 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?

Nowadays we almost always output in parallel on each processor because 
it gives the best performance.

> 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 don't have any results for these benchmarks. You could take a look at 
the disk I/O scaling tests we have performed on our AEI clusters when 
they were delivered. They don't use Cactus but mimic Cactus behaviour 
during a parallel checkpoint.

-- 
Cheers, Thomas.