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Home -> Community -> Usenet -> c.d.o.server -> Re: DB WR PERFORMANCE ON I/O!!!!!!
On Fri, 16 Jul 1999 12:39:45 GMT, naveen_arora_at_my-deja.com wrote:
>Hi,
>I am using Oracle 7.3.3 on unix for a real time system.
>The application mostly involves lot of updates.
>The whole table is in memory and no physical read is there.
>But I/O is hogging resources as db wr always writes after 3 seconds.
>i want to increase this interval or have some get around.
>The platform i am using is fully fault-tolerant so the
>chance of going down is extreamly low.
>If dbwr writes less frequently the I/O will be better.
>Thanks for any help.
In Oracle7, DBWR writes dirty buffers to disks *at least* every 3 seconds. There are a couple of events that will trigger the DBWR to write, but if none of them has activated it in the last 3 seconds then DBWR will fire by itself. AFAIK this time-out interval is not tunable.
But what I can't understand is what makes you think that only DBWR's activity every 3 seconds can make your I/O hogging resources? We are talking about seconds, not milliseconds! In my opinion that would be an example of very idle database (write-vise), as DBWR is triggered only by its time-out and not by the amount of dirty buffers in the buffer cache.
>Naveen
>naveen_at_cdotd.ernet.in
>
>
>Sent via Deja.com http://www.deja.com/
>Share what you know. Learn what you don't.
Jurij Modic <jmodic_at_src.si>
Certified Oracle DBA (7.3 & 8.0 OCP)
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