[Pvfs2-developers] PVFS2 Performance Problem -
dbonnie at clemson.edu
Wed Jul 1 18:15:27 EDT 2009
Sorry for not being clear.
The hardware and software is unchanged. Runs from a few months ago (on
2.8.0) performed as expected. Current runs (on both 2.8.0 and 2.8.1) are
The nodes are sitting there with very low CPU usage even when running the
benchmark. I'm the only one running any jobs and there aren't any processes
running (the system load is < .02 and the cpu usage is pretty much 0%).
The local disks haven't changed and are empty except for the pvfs2 storage
space; performance is bad even when I put the PVFS2 file system storage onto
a very fast (>300 MB/s local bandwidth) Atrato vlun connected over fiber
My initial thought is that some hardware along the line died but I can't
seem to pinpoint it. All of the network interfaces show 0 errors and 0
On Wed, Jul 1, 2009 at 4:10 PM, Rob Ross <rross at mcs.anl.gov> wrote:
> Hi David,
> I still don't get it: when was the performance good? Same software and
> hardware, just some time in the past? Or is there a software change?
> The nodes aren't being used for anything else, there are no rogue
> processes, and the local file systems are otherwise empty?
> On Jul 1, 2009, at 5:05 PM, David Bonnie wrote:
> Rob -
>> Performance is down across all PVFS2 installations. The benchmark simply
>> creates files of a random size (between 1 and 25 MB) in a single folder on
>> the mounted PVFS2 partition, 16 KB at a time. It's not anywhere near ideal,
>> but it's the workload I'm working with.
>> Prior to this problem we were getting ~22 MB/s write throughput and we're
>> down to about 2.5 MB/s for no apparent reason. Reads are down from about 55
>> MB/s to 30 MB/s. No hardware has changed and as far as I can tell no
>> hardware has died either.
>> - Dave
>> On Wed, Jul 1, 2009 at 4:00 PM, Rob Ross <rross at mcs.anl.gov> wrote:
>> Do you mean that 2.8.0 is fast and 2.8.1 is slow? Can you describe the
>> benchmark and how you are doing your measurements?
>> On Jul 1, 2009, at 4:43 PM, David Bonnie wrote:
>> 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!
>> - Dave
>> Pvfs2-developers mailing list
>> Pvfs2-developers at beowulf-underground.org
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