Hi,
The setfattr utility is available in the "attr" package in Debian.
Here are some instructions for changing the default number of datafiles
(ie, the strip count) for a directory:
http://www.pvfs.org/fisheye/browse/PVFS/doc/pvfs2-tuning.tex?r=1.2#l160
And here are some instructions for changing the strip size:
http://www.pvfs.org/fisheye/browse/PVFS/doc/pvfs2-tuning.tex?r=1.2#l227
That will only affect future files that are created in the directory; it
doesn't modify any existing files.
Unfortunately, I don't think there is a good reference for how to select
a strip size. It depends on both your hardware and access patterns.
Most of the time there isn't much reason to change the dfile count. It
used to be helpful to lower it for directories containing small files,
but the file stuffing optimizations in recent versions of PVFS take care
of the most significant cases automatically now. You might find some
benefit to changing it for some special case workloads, but the default
works pretty well for most people.
-Phil
On 03/11/2011 04:07 PM, Matthieu Dorier wrote:
Hello,
The PVFS documentation mentions the possibility to set the
distribution, and the parameters of this distribution (such as the
strip count and strip size), using setfattr. But it seems setfattr is
an external tool, not available on my platform (a Debian linux 2.6)
and I don't find it anywhere on the Internet. Is there any other way
to set these attributes for a given directory, using only what is
provided by PVFS?
Also is there a study or a paper about the influence of such
parameters on the performance with respect to the I/O pattern of the
applications?
Thank you,
Matthieu Dorier
--
Matthieu Dorier
ENS Cachan, antenne de Bretagne
Département informatique et télécommunication
http://perso.eleves.bretagne.ens-cachan.fr/~mdori307/wiki/
<http://perso.eleves.bretagne.ens-cachan.fr/%7Emdori307/wiki/>
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