shmmax !!!

[Venky_1]

Hello,

I need information/clarification on the shmmax parameter. I would like to know what should be the ideal value of shmmax if I have physical memory of 10GB and Oracle processes being used
are highly memory intensive.

Please suggest....

Thanks ..
Venky

[Domenico_5]

another one

The shmmax 'Single shared memory segment' is limited to 1 GB (0x40000000)
on a 32-bit HP-UX 11.0 system. When running under the 64-bit operating
system, shmmax is limited to 1 TB (0x10000000000).

The maximum shared memory accessible (all segments/quadrants) is limited
to 2.75 GB on 32-bit, and 4 TB on 64-bit HP-UX systems.

[Ravi_8]

Hi,

If you are any oracle, irrespective of RAM,
shmmax of 4GB is more enough

[K.Vijayaragavan.]

Hi,

Check the docs at,

http://docs.hp.com/hpux/onlinedocs/os/KCparam.ShMmax.html

-K.Vijay

[Sandip Ghosh]

What version of oracle you are using 32bit or 64 bit?

If you are using 64 bit then no problem But if you are using 32bit you have to use memory windows to increase the shared memory in Oracle.

Sandip

[Wodisch]

Hi,

if you have a system with 10GB of RAM, then you must be running HP-UX11 with 64bit kernel, anyway.
And then a 32bit Oracle make almost never sense IMHO.
So if you are left with 64bit everywhere you just have to care that nobody resets the value of SHMMAX to something smaller than your (free) RAM-size...

Just my $0.02,
Wodisch

[Ross Martin]

If you have 11.11, (aka. 11i) then you may have a problem increasing shmmax beyond 1GB.

This is a known problem.

The fix is to patch with PHKL_24032.

Hope that helps.

Ross Martin

[Ross Martin]

Here is a workaround if you can't access the patch:

The maximum value for shmmax for a 32-bit application is 1 Gb (0x40000000). But
since the maximum for a shared memory segment for a 64-bit application is 4
Terabytes, the following correction can be made to allow this:

1. Edit /usr/conf/master.d/sysv-shm and change:

*range shmmax<=0x40000000
To:
*range shmmax<=0x40000000000

2. Run '/usr/sam/lbin/getkinfo -b'
3. Use SAM to make the desired changed to shmmax


Ross Martin

[UNIXTEK]

Unless you have an enormous database,
set :
shmmax and maxdsiz_64bit to 4GB,
maxdsiz to 1 GB
maxtsiz to 1 GB

My experience tells me that the system
performs best when shmmax and maxdsiz_64bit
are equal.

[Andreas D. Skjervold]

Hi

Just pump it up to your amount of physical RAM, ie 10GB.

This means just that the largest allowable memory segment is 10GB.
What you'll end up using for your Oracle SGA is a different story. This is dependent on the init.ora settings.

Andreas