SHMMAX kernel parameter

[sheevm]

Hi,

Can someone tell me how is SGA_MAX oracle parameter relates to SHMMAX. We have 8GB physical memory in the box. What is the SHMMAX can be set to maximum? HP-UX 11iv2, rp8420 server.

Thanks
kesh

[James R. Ferguson]

Hi:

The 'shmmax' defaults to 1GB with a minimum value of 2048 and a maximum of 0x40000000000 (4,398,046,511,104 decimal).

http://docs.hp.com/en/B2355-60105/shmmax.5.html

Regards!

...JRF...

[sheevm]

Hi James,

Thanks for the response. Does it cause any issues to set the SHMMAX equal to the size of the memory?

Thanks
Raji

[sheevm]

James, Thanks for the response.

Does it cause any issue setting this parameter equal to the size of the physical memory?

Regards,
kesh

[James R. Ferguson]

Hi (again) Kesh:

Like most kernel parameters, this is a fence or limit. You could set it to a value equal to your physical memory if you want, but this doesn't make sense. You wouldn't want one process to be able to create one large shared memory segement equal to all of your physical memory --- assuming that you even could! See the manpage reference I cited for you.

Regards!

...JRF...