Re: db_cache_size, granules and large amount of physical memory

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_at_gmail.com> 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_at_freelists.org [mailto:

> oracle-l-bounce_at_freelists.org] *On Behalf Of *~Jeff~

> *Sent:* Thursday, August 06, 2009 8:43 PM

> *To:* exriscer_at_gmail.com; Oracle-L_at_freelists.org

> *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_at_gmail.com>

>

> 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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