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

From: joel garry <joel-garry_at_home.com>
Date: Wed, 06 Jun 2007 12:16:48 -0700
Message-ID: <1181157408.854294.266660@j4g2000prf.googlegroups.com>


On Jun 5, 5:30 pm, hpuxrac <johnbhur..._at_sbcglobal.net> wrote:
> On Jun 5, 7:53 pm, joel garry <joel-ga..._at_home.com> wrote:
>
>
>
>
>
> > On Jun 5, 2:39 pm, Swoop <s..._at_doesnotwork.com> wrote:
>
> > > 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
>
> > On a 4 processor 8G system with 2 databases (one test) I have:
>
> > bufpages 0 (nbuf*2)
> > dbc_max_pct 50
> > dbc_min_pct 5 (see the kernel help for determining, once you
> > get to a steady state it doesn't matter so much)
> > nbuf 0 "This parameter is for backwards
> > compatibility and should be set to zero because dynamic buffer cache
> > is preferred."
>
> Do you really have dbc_max_pct set to the default of 50?

Yes.

>
> Sounds like you probably have 4 gig of os memory serving as a file
> buffer cache ... why?

Nothing before now ever stimulated me to look at it. Also, not using direct I/O. Unable to test when it was new, due to RAID-5 salespeople having their way.

This crashconf thingy tells me I'm using 1.6G. I'm hoping that's usage rather than just some configuration, but I don't see any such value in the .h file. The man is a bit unclear on that.

>
> Most oracle hpux installs should have the two parameters dbc_min_pct
> and dbc_max_pct set to very close if not the same values

No argument there, although seeing comments elsewhere about setting it so you have good hit ratios doesn't give me the warm'n'fuzzies.

Being able to say "hey, want a couple of free G on the production server?" right before a new division is added might get some notice, even without any business performance issues, so thanks!

jg

--
@home.com is bogus.
http://www.linux.com/article.pl?sid=07/06/05/1728243
Received on Wed Jun 06 2007 - 14:16:48 CDT

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