[Pvfs2-developers] PVFS2 Performance Problem -

[Becky Ligon]

David:

When we were working on Brett's test here, we were told that in 2.8, you
need to use a large block size, even if you are working with small files. 
16K is much too small.  We went to about 4MB.

Becky

> Hello all -
>
> I'm having trouble figuring out a problem with performance depredation on
> a
> simple 10 node cluster.  Prior runs on the cluster (before this problem
> manifested itself) resulted in bandwidth and IOPS about 10 times higher on
> a
> small file creation workload.  Each node is running as a metadata server
> and
> a data server.
>
> The problem is persistent between versions and installations of PVFS2
> 2.8.0
> and 2.8.1.  Rebooting all of the nodes didn't improve anything.  The
> network
> connections (simple GigE) showed no errors or dropped packets.  Using
> different physical disks (both SAS and FC) didn't improve things.  The
> kernel logs didn't show anything out of place nor did the pvfs2 server or
> client logs.  It seems like a network issue but I can't seem to find
> anything wrong with any of the connections.
>
> Has anyone seen this kind of problem before?  I seem to remember something
> on the list before about performance suddenly dropping but I can't find
> the
> message now (of course).  Any insight would be appreciated!
>
> Thanks,
>
> - Dave
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-- 
Becky Ligon
PVFS Developer
Clemson University
864-656-3865