• From: "Kevin Closson" <kevinc@xxxxxxxxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Thu, 27 Jul 2006 08:10:09 -0700

>>>Asynch I/O is not that important. Oracle can emulate it 
>>>using I/O slaves. Granted, it's not as good as the real 

...right, Mladen, it isn't. I wouldn't recommend slaves
as musch as just multiple true writers. With 10g would
can have a more than 10 of them. I routinely test 4 node
Linux RAC on NAS with OLTP workloads that generate ~15,000
I/O sec where ~1000 are LGWR writes and 6,000 are dbwr
writes. In the end if free buffer waits aren't the problem, 
all you are doing is improving (slightly) processor utilization
when you use OS async IO. 

Large SMPs generally benefit more from async IO than commodity
servers, that is true (and I know why, and would love to have
the time to explain why), but most large SMPs out there are
servicing workloads that aren't as I/O intensive as the ones
I test PolyServe Scalable NAS with (HP EFS-CG). Just look at
the numbers.

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