Re: db_cache_size, granules and large amount of physical memory
- From: LS Cheng <exriscer@xxxxxxxxx>
- To: Jinwen Zou <kevin.j.zou@xxxxxxxxx>
- Date: Fri, 7 Aug 2009 18:14:38 +0200
Hi
The granule is 4M, I will double check that on Monday.
So in my case it looks that db_cache_size is number of cpu * granule, will
double check this too on Monday
Thanks!
--
LSC
On Fri, Aug 7, 2009 at 1:38 AM, Jinwen Zou <kevin.j.zou@xxxxxxxxx> wrote:
> From oracle reference:
>
> >>
>
> The value (of db_cache_size) must be at least *4M** * number of cpus *
> granule size* (smaller values are automatically rounded up to this value).
> A user-specified value larger than this is rounded up to the nearest granule
> size. A value of zero is illegal because it is needed for the DEFAULTmemory
> pool of the primary block size, which is the block size for the
> SYSTEM tablespace.
>
> <<EOF
>
>
>
> The 4M should be 4 I think.
>
>
>
> Thanks,
>
> Jinwen
> ------------------------------
>
> *From:* oracle-l-bounce@xxxxxxxxxxxxx [mailto:
> oracle-l-bounce@xxxxxxxxxxxxx] *On Behalf Of *~Jeff~
> *Sent:* Thursday, August 06, 2009 8:43 PM
> *To:* exriscer@xxxxxxxxx; Oracle-L@xxxxxxxxxxxxx
> *Subject:* Re: db_cache_size, granules and large amount of physical memory
>
>
>
> Hi LS
>
> We had similar issues on a T5140 ... IIRC the fix involved setting the
> cpu_count to a more 'sane' value. Our problem was actually the minimum SGA
> being too large to allow the necessary number of instances on the server.
>
> If you run utlrp.sql it will go a bit nuts with such a big cpu_count as
> well, as it has some default parallelism built in to it...
>
> I'm pretty sure the above is right, though I'm not at that client anymore.
>
> HTH!
>
> Jeff Wong
>
>
>
> 2009/8/6 LS Cheng <exriscer@xxxxxxxxx>
>
> Hi
>
> I am working with several Sun M9000 servers, it looks like that
> db_cache_size has quite large default values (even set to a low value) when
> the server has a large amount of physical memory.
>
> For example:
>
> server 1 has 16 quadcore Sparc 960MHz with threading on so it shows 128
> CPU, with 512GB physicla memory
> server 2 has 4 quadcore Sparc 960MHz with threading on so it shows 32 CPU,
> with 128GB physicla memory
>
> When db_cache_size is manually set to 64MB in server 1 it actually uses
> 512MB and server 2 128MB.
>
> Is there anyway to decrease this default limit?
>
>
> TIA
>
> --
> LSC
>
>
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