[Pvfs2-users] File affinity and CPU resource scheduling concerns when using compute node as a PVFS server

[Rob Ross]

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 could be way out of date.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