If the files are being created serially, you could use the "change the
directory attributes" approach. Again, those attributes are only used
at the time the file is created; if they are changed afterwards, they
only impact files created after the change.
Might be easier to just use different directories for your different
files...
Rob
On Jan 23, 2009, at 3:15 PM, FileSystem Novice wrote:
Thanks for the clarification, Brad & Rob.
Regarding the 3 ways suggested to accomplish this, the 2nd one
probably won't work for our system (when multiple files with
different distribution parameters need to be written onto the same
directory).
On Fri, Jan 23, 2009 at 3:38 PM, Rob Ross <[email protected]> wrote:
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
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