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

From: joel garry <>
Date: Tue, 05 Jun 2007 17:59:26 -0700
Message-ID: <>

On Jun 5, 5:27 pm, hpuxrac <> wrote:
> On Jun 5, 6:01 am, Swoop <> 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
> > 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
> I would recommend setting the dbc_max_pct very close to the
> dbc_min_pct otherwise hpux tends to keep increasing the size up to the
> dbc_max_pct.
> If you take the default value of 50 for dbc_max_pct that will have 2
> gig of os memory file caching that oracle ( hopefully if you have
> configured your oracle correctly ) won't even use.

Since it probably looks like I'm giving opposite advice to this, I should say, any time hpuxrac and I appear to disagree about hp-ux, listen to him :-)

In my customer's case, it is a fast set of processors with a not-so- fast RAID-5, and happens to work well with defaults (at least, no complaints - I have seen the hardware get behind on massive loads). I would rather do it the "correct" way, but there you go. It doesn't seem to be wasting memory, I would like to know how one might tell without glance (an optional utility). I understand about double buffering being wasteful, but I also understand about tuning that which is not a bottleneck being useless.

Swoop, Metalink Note:401323.1 helps clarify the vfxs options.

> Probably 256 meg or less ( 128 maybe ) if is adequate so figure out 4
> gig times what number gives you that and set both dbc_max_pct and
> dbc_min_pct to the same value.
> The other ones I would have to double check at work tomorrow but I
> think they both should be zero.
> Check out the hp documentation just do a google on dbc_max_pct


-- is bogus.
Received on Tue Jun 05 2007 - 19:59:26 CDT

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