Re: high log file sync wait
From: Andreas Piesk <a.piesk_at_gmx.net>
Date: Fri, 30 Nov 2012 19:39:27 +0100
Message-ID: <50B8FD5F.1020003_at_gmx.net>
On 30.11.2012 03:03, Suya wrote:
> I agree that the time of 40 ms means the log file write operation is slow,
> but I am trying to figure out which stage is slower and how to fix it. As
> we can see that the log file parallel write wait is only 6.52 ms which is a
> reasonable value for I/O latency. thus I don't think it's a purely I/O
> problem.
Date: Fri, 30 Nov 2012 19:39:27 +0100
Message-ID: <50B8FD5F.1020003_at_gmx.net>
On 30.11.2012 03:03, Suya wrote:
> I agree that the time of 40 ms means the log file write operation is slow,
> but I am trying to figure out which stage is slower and how to fix it. As
> we can see that the log file parallel write wait is only 6.52 ms which is a
> reasonable value for I/O latency. thus I don't think it's a purely I/O
> problem.
so the write is fast, but the sync is slow? i have a similar OLTP system which does basically nothing else then writing and committing transaktions.
what platform do we speak of?
Have you tried putting LGWR in the RT schedule class? i've seen some improvement by doing so, even
with a lot of idle cpu.
what's the situation if you shut down 3 nodes and use only 1 node? Better, worse?
Regards,
-ap
-- http://www.freelists.org/webpage/oracle-lReceived on Fri Nov 30 2012 - 19:39:27 CET