Hi Chris,
Yes, you can certainly run PVFS servers on compute nodes. That's what
we used to do all the time back in "the day", but it's still possible.
The file system does not migrate files. In part this is because it
would dramatically complicate metadata management, in part because we
are frequently running in environments where there's no locality to
exploit.
You can choose to distribute over fewer (or just one) node, and there
is functionality to discover where a file is stored, so you can map
your computation onto the storage.
Obviously yes, doing work on some other node will slow down
computation on that node, how much depends on many things.
Rob
On Oct 21, 2009, at 12:40 PM, Chris Worley wrote:
I haven't looked at PVFS for nearly a decade, so my understanding
could be way out of date. Sorry if this is a stupid question; I'm
hoping PVFS might fill some requirements I'm looking at.
Is it typical to use compute nodes as PVFS file servers? Is it even
possible (i.e. it isn't w/ Lustre)?
If so, while striping across I/O nodes looks to be the default, is
there any provision for file affinity... i.e. files migrating to the
nodes using them?
If striping is the only choice, and compute nodes serve the I/O too,
then a job running on one set of nodes could be using files striped
across another set of nodes in use by another job, causing both jobs
to loose performance, correct?
Are there any links to PVFS performance over IB?
Thanks,
Chris
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