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Re: Insert takes too much time

From: Tom Pall <tom_at_cdproc.com>
Date: Thu, 2 Nov 2000 18:01:54 -0600
Message-Id: <10668.121019@fatcity.com>


Oracle's rationale for enabling async i/o for Solaris is that if you have one or more files raw, the async i/o will go to work there. Further, the async i/o failure should happen very, very fast.

_However_, people have experienced delays in the async i/o attempts failing. Not wanting to waste time, I disable async i/o in my initialization files. You might want to do the same. It may not help, but it sure shouldn't hurt.

I had many go arounds with Oracle Support a year or two ago about multiple dbwriters vs. dbwriter slaves. Articles in Metalink and Oracle Support favor multiple dbwriters instead of dbwriter slaves. I use multiple dbwriters and they work great. There have been, with Oracle 8, certain issues with dbwriter slaves which are not seen with multiple dbwriters.

Your mileage may vary...

> Tom,
>
> Very interesting. I'm new to Solaris, and have been less than impressed
> with the performance we're getting. I bought Adrian Cockcroft's "Sun
> Performance" book and have learned quite a bit, but I'm still not quite
> where I feel I need to be. We've got an EMC Array, which further
> complicates things because so many "traditional" I/O troubleshooting options
> are negated by the manner in which the array operates.
>
> Would I be better off setting the init.ora parameter disk_asynch_io to false
> and using dbwr_io_slaves?
>
> Any thoughts on this would be appreciated.
>
> David A. Barbour
> Oracle DBA - ConnectSouth
> 512-681-9438
> dbarbour_at_connectsouth.com
>
>
> -----Original Message-----
> Sent: Thursday, November 02, 2000 3:30 PM
> To: Multiple recipients of list ORACLE-L
>
>
> By default, Solaris does async i/o. At least it tries to. The async calls
> fail quickly and Oracle retries with synch i/o.
>
> Async i/o works on NT.
> ----- Original Message -----
> To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
> Sent: Thursday, November 02, 2000 11:56 AM
>
>
> > Hi all,
> >
> > I have two machines - NT4 (8.1.5.1) and Sun Solaris 2.7 (8.1.6). They both
> > give same I/O performance outside of Oracle (on both read and write
> tests).
> >
> > When running simple procedure that inserts 10,000 / 100,000 / 1,000,000
> rows
> > into a simple table without indexes, I get results 3 times faster on the
> NT
> > machine.
> >
> > Both instances have almost the same oraini. Of course the Solaris has
> better
> > parameters on memory and cpu parameters, as it should be.
> >
> > Do you have any idea why there's a slight performance difference between
> the
> > machines , and why the Sun is slower?! it's configuration should be at
> least
> > as good as the NT.
> >
> > Thanks,
> >
> > Ronen Levit
> > Database team leader
> > www.talmai.com
> > T: +972 8 9460606 #212
> > F: +972 8 9460705
> > C: +972 52 448699
> >
> >
> > --
> > Please see the official ORACLE-L FAQ: http://www.orafaq.com
> > --
>
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Tom Pall
> INET: tom_at_cdproc.com
>
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> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: David Barbour
> INET: DBarbour_at_connectsouth.com
>
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Received on Thu Nov 02 2000 - 18:01:54 CST

Original text of this message

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