Hi Matthieu,
I'm probably too late chiming in, but if you specifically want to
specify the list of servers and the stripe size, you might want to look
at these two specific examples in the src/apps/admin directory:
- pvfs2-touch: the -l option allows you to specify the list of servers
- pvfs2-cp: the -s option allows you to specify the strip size
I don't see an example that does both simultaneously, but if you combine
the layout options from the former and the distribution options from the
latter it should do what you want :)
It probably mentions this on the wiki somewhere, but both the layout and
distribution (strip size) parameters must be set at file creation time.
You cannot modify those parameters for an existing file.
-Phil
On 02/07/2013 11:53 AM, Becky Ligon wrote:
Matthieu:
Look at the Orangefs.org wiki page on distributions and layouts. This
page describes how you can specify the different options when creating
a file using the API.
(http://www.orangefs.org/trac/orangefs/wiki/Distributions)
Becky
On Thu, Feb 7, 2013 at 11:37 AM, Kyle Schochenmaier
<[email protected] <mailto:[email protected]>> wrote:
Hi Mattieu -
I'm not sure if a 0 size will work, in fact, if it wasnt designed
in it may crash things (I havent looked at this distribution's
code in years).
Moreover, the server numbers you're seeing in the example are the
servers in the 'stripe' but may not correspond to the logical
server numbers that you're thinking of.
This is because the '0th' server in the stripe is determined
randomly among the set of servers in the filesystem and
intentionally changes so as to avoid hitting the same server
repeatedly for every file creation, or in the case of many small
files that dont fill an entire stripe this prevents uneven
distribution of the file handles.
Regards,
~Kyle
Kyle Schochenmaier
On Thu, Feb 7, 2013 at 10:30 AM, Matthieu Dorier
<[email protected] <mailto:[email protected]>> wrote:
Hi Kyle,
Thank you for the advice, these codes should be indeed a good
place to start.
Regarding the distribution, I dug a bit and found here
http://www.orangefs.org/doxygen/index.html some functions to
set/get extended attributes (e.g. pvfs_fsetxattr). Then at
http://www.pvfs.org/cvs/pvfs-2-8-branch-docs/doc/pvfs2-tuning/pvfs2-tuning.html
in section 7.4 I see a way to set the stripe size on a
per-server basis so I guess I could put 0 for the servers I
don't want to use and a positive value for the servers I want
to use. Would that work?
Thanks,
Matthieu
------------------------------------------------------------------------
*De: *"Kyle Schochenmaier" <[email protected]
<mailto:[email protected]>>
*À: *"Matthieu Dorier" <[email protected]
<mailto:[email protected]>>
*Cc: *"pvfs2-users" <[email protected]
<mailto:[email protected]>>
*Envoyé: *Jeudi 7 Février 2013 17:05:06
*Objet: *Re: [Pvfs2-users] Using PVFS2's API directly
Hi Matthieu -
For API examples I would start with looking at the admin
tools like pvfs2-cp, etc as they utilize the libpvfs apis
directly.
I'm not sure if you're able to specify any of the
information you want to on a per-file basis at creation time.
This information is pulled in from the distribution params
of the directory the file is created in. There may be
other methods I'm not immediately thinking of though...
I'll let others comment.
~Kyle
Kyle Schochenmaier
On Thu, Feb 7, 2013 at 7:05 AM, Matthieu Dorier
<[email protected]
<mailto:[email protected]>> wrote:
Hi,
I would like to use the client API provided by PVFS2,
without any kernel support or MPI-I/O interface. Where
can I find documentation and code samples of this API?
Also I'd like to know if there is a way to specify,
when creating a file (so from within a client
application), the list of storage servers to which
this file should go and the stripe size, in order to
bypass the configuration of the directory in which the
file is created?
Thanks!
Matthieu Dorier
PhD student at ENS Cachan Brittany and IRISA
http://people.irisa.fr/Matthieu.Dorier
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--
Becky Ligon
OrangeFS Support and Development
Omnibond Systems
Anderson, South Carolina
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