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To return to this discussion, in recent testing, I have found that
writing to a Lustre FS via a higher level library, like PNetCDF, fails
because the default for value for romio_ds_write is not disable. This
is set in the mpich code in the file
/src/mpi/romio/adio/common/ad_hints.c<br>
<br>
I believe it has something to do with locking issues. I'm not sure how
best to handle this, I'd prefer the data sieving default be disable,
though I don't know all the implications there. Maybe an ad_lustre_open
should be a place where the _ds_ hints are set to disable.<br>
<br>
Marty Barnaby<br>
<br>
<br>
Weikuan Yu wrote:
<blockquote cite="mid:47D7CD00.4070703@gmail.com" type="cite">
<pre wrap="">Andreas Dilger wrote:
</pre>
<blockquote type="cite">
<pre wrap="">On Mar 11, 2008 16:10 -0600, Marty Barnaby wrote:
</pre>
<blockquote type="cite">
<pre wrap="">I'm not actually sure what ROMIO abstract device the multiple CFS
deployments I utilize were defined with. Probably just UFS, or maybe NFS.
Did you have a recommended option yourself.
</pre>
</blockquote>
<pre wrap="">The UFS driver is the one used for Lustre if no other one exists.
</pre>
<blockquote type="cite">
<pre wrap="">Besides the fact that most of the adio that were created over the years are
completely obsolete and could be cleaned from ROMIO, what will the new one
for Lustre offer? Particularly with respect to controls via the lfs utility
that I can already get?
</pre>
</blockquote>
<pre wrap="">There is improved collective IO that aligns the IO on Lustre stripe
boundaries. Also the hints given to the MPIIO layer (before open,
not after) result in lustre picking a better stripe count/size.
</pre>
</blockquote>
<pre wrap=""><!---->
In addition, the one integrated into MPICH2-1.0.7 contains direct I/O
support. Lockless I/O support was purged out due into my lack of
confidence in low-level file system support. But it can be revived when
possible.
--
Weikuan Yu <+> 1-865-574-7990
<a class="moz-txt-link-freetext" href="http://ft.ornl.gov/%7Ewyu/">http://ft.ornl.gov/~wyu/</a>
</pre>
</blockquote>
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