[Pw_forum] Ways to reduce disk i/o when doing phonon calculations with ph.x

Hans Lind halin at ifm.liu.se
Tue Aug 2 12:04:41 CEST 2011


When doing large phonon calculations (dozens of atoms, distributed over
1000s of nodes) ph.x ends up doing a very large amount of disk i/o. This
wouldn't be so much of a problem on systems with distributed disks, each
node having access to its own hard drive. But on systems with a central disk
the i/o causes system wide slowdowns as the disk can't keep up. Is there
some way to reduce the disk i/o to manageable levels, I have tried setting
"reduce_io='low'" but it is just not enough. Or do I have to resort to using
distributed disk systems?. Are the developers working on some way to reduce
the disk i/o in future versions?
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