I am trying to use LLNL's mdtest
[http://sourceforge.net/projects/mdtest/] on pvfs2.
It works by passing an argument to the test indicating which directory
the test must run. However when I do indicate the directory as
/mnt/pvfs2 - the test runs on the local directory and doesn't use PVFS2.
If I do add the prefix , as "pvfs2:/mnt/pvfs2" , the test reports back
that it cannot find the filesystem. Although my mpich libraries are
linked with the pvfs2 libraries.
Any ideas about this?
Yep, LLNL''s mdtest uses MPI for coordination but POSIX for metadata,
so the 'pvfs2:' prefix won't work for that test (it works for the
mpi-md-test in the PVFS CVS).
What version of mdtest are you using? You are giving mdtest the '-d'
option? I can't think of a reason for mdtest to ignore your testdir
option and start doing stuff in the local directory...
I apologize for the delay in replying.
I use version 1.7.4 - which seems to be the latest build on their
sourceforge page.
The mdtest does not ignore my prefix option. Here's what happens. AFAIK,
while using PVFS2 on a cluster there is no requirement to perform a
mount operation. As I understand since the MPICH binaries are linked to
the PVFS2 libraries, the MPI app/bechmark would understand how to locate
the PVFS2 storage servers [apart from the /etc/pvfs2tab content] .
Hence there exists a directory /mnt/pvfs2 on each of my compute nodes.
Hi Nirmal,
Your assumption is only true if the MPI app/benchmark uses functions
like MPI_File_open(), MPI_File_write(), etc. to access the file system.
Those functions are part of the MPI-IO interface. mdtest does not do
this. In mdtest.c it is just doing normal open() and write() calls.
You therefore won't be able to use mdtest to test PVFS unless you mount
the PVFS file system. As you are running it right now it is probably
just creating files in your local file system under /mnt/pvfs2, which is
why they don't show up in pvfs2-ls.
-Phil
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