Re: Why do I get out of memory errors when 10GB memory is free?

From: zigzagdna <>
Date: Wed, 15 Jul 2009 07:15:07 -0700 (PDT)
Message-ID: <>

On Jul 15, 7:57 am, John Hurley <> wrote:
> On Jul 14, 9:56 pm, zigzagdna <> wrote:
> snip
> > > The HP engineer should be able to work with you going thru the hp ux
> > > oracle customization doc and checking and then double checking
> > > everything.
> > > Good luck and keep us posted.
> > First HP engineer reduced  kernel parameters for UNIX buffers, so
> > kernel occupies less memory. Hope was that it will make more memory
> > avaiable for application (which it did), but it did not fix the
> > problem. Subsequntly. swap space was increased.
> > Swap space increase fixed the rroblem . I am not a UNIX admin, so I
> > still wonder when 10GB memory is avaiable why HP OS first won't
> > utlize  this memory instead of going to swap to get heap memory .  We
> > did not change  maxdsiz, maxssiz or maxtsiz prameters.
> > I am glad problem is now resolved. I can put more oracle instances on
> > the server and get my company money's worth.
> The hpux kernel parameters dbc_max_pct and dbc_min_pct come out of the
> box with values that reserve huge chunks of memory for unix buffering
> that are pretty much unacceptable for any database server and pretty
> much have to be checked and revised downward.
> On a machine with 16 gig of memory or more I would really hope you
> have them down to like 5 or so ... with 24 gig of memory like 2 or 3
> would be probably a good value.  You can find postings on this topic
> in cdos from a while back but well not many hpux questions come into
> here.
> As an oracle dba running on unix or linux ... you just have to ante up
> and take responsbilitity for reviewing and being at least somewhat
> knowledgeable about setting and reviewing this stuff.
> Why?  Because no one else is likely to care enough or be competent
> enough to take the time and assess what should be done.
> Oracle has documented pretty well the relevant things that should be
> checked and in most cases provides hints about checking related things
> like dbc_***_pct ( as far as I can recall ).  HP provides white papers
> etc that are also related to tuning kernel stuff when running oracle.
> Are you using direct IO and avoiding the unix buffer cache?  Do you
> even know what to look at to find out the answer to this question?
> Before you think you are done here I would take a look at that area
> immediately.
> The whole subject of how many instances one puts onto a dedicated
> server also deserves some consideration and review.
> Good luck!- Hide quoted text -
> - Show quoted text -

Regraidng reducing UNIX buffers, we typically reduce them if server does not have lot of memory.

I am still puzzled why increasing swap will fix the problem when server alreday has 10GB memory free.

Prem Received on Wed Jul 15 2009 - 09:15:07 CDT

Original text of this message