[Swift-devel] GPFS issue of SWIFT on BGP

[Ben Clifford]

On Tue, 10 Feb 2009, Zhao Zhang wrote:

> > > Here we got an old problem, all IO nodes are trying

> data transfer from  I/O nodes to submit-side client is  writing to GPFS
> through ssh-provider.

By 'old problem' I assumed you meant the GPFS locking problems previously 
experienced, where GPFS locks for particular filesystem objects would 
need to be expensively moved between nodes.

However, that should not be a problem here - from the GPFS perspective, 
the submit (login) node is the only node that is interacting with GPFS, 
and the only node that needs a lock on that directory.

If you're experiencing slowness, then I would be inclined to investigate 
elsewhere. It may be that the ssh provider is not fast (ssh is not 
renowned for being a fast protocol; Mihael might have some commentary 
either way based on his experiences with the cog ssh provider); it may be 
that something else is causing a bottleneck.

Do you have any detailed timing information? (from my perspective, the 
wrapper logs for every job, and the submit side log, would be interesting 
to look at - send those to me)

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