[CentOS] 3Ware 9550SX and latency/system responsiveness

Ross S. W. Walker rwalker at medallion.com
Tue Oct 2 13:41:25 UTC 2007

Simon Banton wrote:
> At 09:24 -0400 2/10/07, Ross S. W. Walker wrote:
> >Actually the real-real fix was to use the 'deadline' or 
> 'noop' scheduler
> >with this card as the default 'cfq' scheduler was designed 
> to work with
> >a single drive and not a multiple drive RAID, so it acts as 
> a govenor on
> >the amount of IO that a single process can send to the 
> device and when
> >you do multiple overlapping IOs performance decreases instead of
> >increases.
> Ah - that wasn't actually a complete fix Ross, but it did give a 
> noticeable improvement in certain situations. I'm still chasing a 
> real real 'general purpose' fix.

I was unaware of that. I thought changing schedulers did it.

What is the recurring performance problem you are seeing?


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