Re: Pluggable database in 12C

From: Noons <>
Date: Tue, 23 Oct 2012 16:46:18 +1100
Message-ID: <k65avb$4d4$>

John Hurley wrote,on my timestamp of 23/10/2012 11:51 AM:

> ... Log file sync wait time dropped from around 2-3ms to under 1ms for
> 90% of the time. CPU use dropped nearly 25% for same workload. I/O is
> similar, no major alterations.
> Interesting but keep in mind that we are at the mercy of Oracle
> instrumentation here at least for how they measure the log file sync
> wait time. Lots of possible ways internally that Oracle might have
> changed how they measure it between ( well off some of the
> final 10.2 code ) and

Indeed, good point. Given they always recommend we use their metrics, we're at their mercy on SQL-related counters.

But CPU and I/O above was measured through Unix, not Oracle. Backups for example were considerably faster on wall clock time (30 minutes less on 3.5 hours) and the overnight batch run has significantly reduced its runtime as well.

One thing that I'm experimenting with at the moment is the new (11.2) RMAN compression algorithms. The LOW compression setting gives me a backup that is half the time (1.5h from 3), with considerably less CPU use and a backup file size less than twice what it was: 250GB from 180GB. I/O has of course increased but I've got oodles of bandwidth so it's not a problem.

I've now majorly reduced the CPU usage during the DW backup window, which is excellent as that is the batch window for our JDE system and I can re-allocate the CPU where it's needed.
One of the advantages of running db servers on vios inside Aix is that the OS can dynamically (within defined constraints) re-apportion CPU, memory and I/O channels and give them where it's needed. By saving on backup overhead, I've freed resources that can immediately be used in other vio virtual boxes.

Man! I love this "private cloud" virtualization stuff!! ;-) (mind you: we used to do exactly this in the mainframe and VM/370 days - the more IT hardware/software evolves, the more it is the same...) Received on Tue Oct 23 2012 - 07:46:18 CEST

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