Re: ASM parameters
Date: Sat, 26 Jan 2008 10:38:53 -0800 (PST)
Message-ID: <d4fd6b56-14ee-4ab2-aba9-4b6f7ca1ed4d@u10g2000prn.googlegroups.com>
On Jan 25, 3:46 am, Mladen Gogala <mgog..._at_yahoo.com> wrote:
> 10.2.0.3 on RH Linux 4.0, update 4, 2 node RAC. I am experimenting with
> ASM parameters, DB_CACHE_SIZE and DB_FILE_MULTIBLOCK_READ_COUNT.
> Default cache size is 25M, MBRC is 110. Default block size is 4k.
> I have set cache size to 128M, MBRC to 256 (1M reads). I tried going above
> 1M, but the parameter was ignored. RMAN seems to work much faster,
> benchmark is in progress. Does anybody have any recommendations or
> experiences to share?
>
> --
> Mladen Gogalahttp://mgogala.freehostia.com
Increasing dfmbrc only works up to a point. Tom Kyte has written a bunch about it and has some test scripts and methodology that shows ( varies by os if I remember correctly ) bumping it up only works to a point. ( I think the book is Expert One on One ... can't check my work bookshelf right now ).
If you combine changing dfmbrc and setting oracle 10046 traces you can see that at some point increases are ignored ( maybe better wording is no longer applicable ).
Whether you are using ASM or doing IO directly from a database instance it probably works the same way would be my guess. Received on Sat Jan 26 2008 - 12:38:53 CST