From: Anton Dischner (Anton.Dischner_at_med.uni-muenchen.de)
Date: Tue Sep 30 2003 - 10:30:26 CEST
Date: Tue, 30 Sep 2003 10:30:26 +0200 From: Anton Dischner <Anton.Dischner@med.uni-muenchen.de> Message-ID: <BB9F0BC2.C2EF%Anton.Dischner@med.uni-muenchen.de> Subject: Re: [suse-oracle] enabling async IO, performance questions
Hi,
i have 2 Quad Xeon plenty of RAM connected to RAID 5 via 3 channel SCSI.
Performes very well. Async off.
I have a new dual Xeon (faster) 2 GB RAM connected to a fibre channel RAID.
Standard was async off.
System performance with one user was great.
A soon as i tried to log in as a second user i had to wait for approx 30-60
seconds just for the logon!
With the help of Oracle support we quickly found that system is waiting on
i/o very heavily.
Doing statspacks is very helpful.
db file sequential reads was 92 % of time.
Turning async i/o solved the problem.
The system now runs very performant.
Another performance boost was changing write through to write back of
the RAID 5. Yes i know for the sake of security.
regards,
Toni
-- +--------------------------------------------------------------------+ | Anton Dischner, Unix admin, Oracle-DBA Phone: +49 89 70953202| | Institut fuer Klinische Chemie Fax : +49 89 70958888| | Klinikum Grosshadern Home : +49 89 69708766| | Ludwig Maximilians Universitaet Muenchen Mobil: +49 172 8388880| | 81366 Muenchen Germany | | Marchioninistr. 15 dischner at med.uni-muenchen.de| +--------------------------------------------------------------------+ > 1.) Can the experienced folks give any indication as > to how enabling async IO can improve performance, i.e. > roughly speaking by what factor can it improve, given > that all other factors are left alone ? ... -- To unsubscribe, email: suse-oracle-unsubscribe@suse.com For additional commands, email: suse-oracle-help@suse.com Please see http://www.suse.com/oracle/ before posting
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