Oracle Apps 12.1.1 shmseg 512 from 300 (12.0.4)

[Asra]

Release 12.1.1 Oracle Application (metalink doc#762891.1) suggests setting the Kernel param shmseg to 512. In release 12.0.4 for HP-UX it was 300 (Note#402307.1). Any idea why the increase?

[James R. Ferguson]

Hi:

Oracle is a memory-hungry beast, but then that's one of the things that makes it run faster.

The 'shmseg' kernel parameter controls the number of shared memory segments an individual process may have. I would certainly follow Oracle's recommendation/requirement in this regard.

http://www.docs.hp.com/en/B3921-60631/shmseg.5.html

Regards!

...JRF...

[Asra]

My question is - Is there any particular reason that from 12.0.4 to 12.1.1 the shmseg has increased from 300 to 512. While I understand that following the doc is the right thing to do but increasing the shmseg to 512 really requires some justification than just that the note says so.

[Duncan Edmonstone]

>> increasing the shmseg to 512 really requires some justification than just that the note says so.

Does it? SO if the note also said "you require an extra 1GB of disk space", you'd query that too would you?

When my car dealer says "put unleaded gas in your new car", I don't say "what's the justification for that", I just know that its the right thing to do. One would "imagine" that the reason for the increase is that v12.1.1 uses more shared memory segments that version 12.0.4, otherwise why would oracle make the recommendation?

If you need to know more, I's suggest opening a TAR with oracle rather than trying to get anything other than conjecture on these forums...

HTH

Duncan

[Asra]

When my car dealer tells me to put unleaded at 25% extra cost, hell I would ask him why? Not because I question his knowledge or authority on the matter, but because I would like to know what the change would mean - the monetary, value addition and everything else. Consider it curiosity or inquisitivity.

And it is Oracle support that redirected me to HP saying it was as per "recommendation of HP" .

[Steven E. Protter]

Shalom,

There are a number of parameters that Oracle recommends for increase on the application server.

Before you dis me with 0 points, I have five years experience installing this product.

I recommend exceeding the minimum Oracle requirements, because Oracle application server is not the only application using these resources.

shmmax should be at least 50% of physical memory or Oracle recommendations which ever is higher.

You may want to scale back dbc_max_pct and dbc_min_pct as they use memory that the Oracle application server can utilize more effectively.

A book can be written on this.

Oracle Application Server uses shared memory to pass data. It needs lots of shared memory and the ability to have lots of shared memory segments.

Other standard apps need shared memory segments and I from experience set that number around 2000.


As to your comments:

When my car dealer tells me to put unleaded at 25% extra cost, hell I would ask him why?

Your car dealer is part of an industrial complex (oil and auto) that wants to rip you off as a consumer.

Oracle is actually making recommendations based on lab testing experience.

Not because I question his knowledge or authority on the matter, but because I would like to know what the change would mean - the monetary, value addition and everything else. Consider it curiosity or inquisitivity.

And it is Oracle support that redirected me to HP saying it was as per "recommendation of HP" .

For once I'm on Oracle side.

SEP

[James R. Ferguson]

Hi (again):

Duncan summarized it best for you, though you clearly don't like his or my answer. Duncan wrote:

"I suggest opening a TAR with oracle rather than trying to get anything other than conjecture on these forums..."

Why don't you enhance the value of this thread by _doing_that_ and reporting what the Oracle position is on the subject. In that way future readers might benefit more than our mere conjecture?

...JRF...