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Re: Kernel parameter recommendations for HP-UX 11.11 in regard to SGA size

From: Swoop <swoop_at_doesnotwork.com>
Date: Wed, 06 Jun 2007 07:39:37 +1000
Message-ID: <4665d7bf$0$17158$afc38c87@news.optusnet.com.au>

sybrandb wrote:
> On Jun 5, 12:01 pm, Swoop <s..._at_doesnotwork.com> wrote:

>> I'm knew to HP-UX and was just after some advice in regards to some
>> kernel parameters. I've done a fair bit of research but some of the
>> things I've read seem to conflict and because lower versions of the OS
>> have different settings and because the amount of RAM on the boxes (that
>> they are configuring) differ it is hard to peg it down.
>>
>> For example, a metalink document recommends setting the system buffer
>> cache to a maximum of 128M but it says this for a low amount of RAM,
>> however, it doesn't specify what it means by low :(
>>
>> I'll be testing it out first on a test box.
>>
>> 2 processor box, HP-UX 11.11
>> 4Gb RAM
>> Running 9.2.0.8
>> vxfs filesystem
>> Running four databases (largest is 30Gb, others are 2Gb) as a pure
>> database server
>>
>> Just wondering how others have configured the following parameters
>>
>> bufpages
>> dbc_max_pct
>> dbc_min_pct
>> nbuf
>>
>> in regards to system buffer cache?

>
> You need to configure the databas filesystems for directio, as Oracle
> already has a buffer cache.

Unfortunately I cannot do this at this time for reasons outside of my control :(

> The above parameters are referring to the *O/S* buffer cache, which
> you shouldn't use.

The OS needs to have an appropriately sized buffer cache even if this is quite small. This is the main part of my question. What is an appropriate size with 4Gb RAM on a pure database server?

> You need to read up the *platform specific* documentation for HP-UX
> available on http://otn.oracle.com (tahiti.oracle.com only has generic
> docs)

I have read the platform specific data which did mention many kernel parameters but not the ones listed above :(

>
> Four databases on 4 Gb RAM is a recipe for disaster.

Unfortunately most companies live far from a perfect world and thus a DBA has to work with the resources that she/he currently has. In the role that the databases are being used for, 4Gb is adequate. Adequate being measured in user response time.

>
> --
> Sybrand Bakker
> Senior Oracle DBA
>
> Fact: 99.9 percent of all questions on any Oracle forum have already
> been asked and answered over and over again. This is because most
> posters think they are the first to run into a problem and
> consequently don't search Google.
> They are wrong: they are not unique, they are with *too many*
>
>
Received on Tue Jun 05 2007 - 16:39:37 CDT

Original text of this message

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