[Pvfs2-users] Striping in PVFS2 on a per-file basis

[Rob Ross]

On Jan 23, 2009, at 2:09 PM, Kyle Schochenmaier wrote:

> You are spot-on with your assesment of the striping in PVFS2.
> Each file gets a round-robin striping based on the distribution
> parameters of its directory.
> To my knowledge, you cannot set things on a per-file basis, as the
> distribution is done on a per-directory basis.
> If I'm wrong, everyone please feel free to flame me ;-)

Distributions are defined on a per-file basis. The attributes on the  
directory are used as hints on what distribution parameters to use for  
files when they are created.

There are at least three ways then to accomplish what you're thinking  
of (different distributions for different files):
- use MPI-IO and specify distribution parameters as hints; they will  
be used to create the file with a specific distribution
- change the attributes on the directory before you create a file, so  
they match what you want
- use pvfs2-cp "-s" and "-n" options to specify your desired  
parameters, copy an empty file, then write your data into the file  
with whatever app you like

Rob