On Thu, Oct 15, 2009 at 12:53:41PM -0700, Robinson, Eric wrote:
> > That's a kernel/performance issue. Perhaps there's an issue 
> > with the storage driver. The fact that the load seems to be 
> > low is probably because the metrics you're looking at are 
> > misleading. For instance, the first delay occurs around the 
> > time the backup client starts and it usually starts by scanning 
> > all filesystems which probably means many small storage requests. 
> > The later load is probably due to big I/O (file transfer) and it 
> > seems to bother the kernel a bit less than the former one.
> 
> If I understand you correctly, when the load shows high it is because
> the kernel is reporting it correctly, but when the load shows low it is
> because the kernel is not reporting it correctly? If so, then sar and
> top cannot be relied upon. If there another way to get to the heart of
> the issue?

That was just the only way I could explain what is going on. Of
course, I may be wrong :)  I don't really know if the high I/O
load of that particular kind (at the start of backup) is
reflected in the metrics you've shown. Best to ask on the kernel
list.

Thanks,

Dejan

> --
> Eric Robinson
> 
> 
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