Thumbrule to size SGA

[Kamkan]

Hi frnds,
Is there any standard policy/thumbrule to size the SGA. How do i size memory structures based on number of expected users? Will that be a right move?

Thanks,
Kam

[yxez]

Hi Friend,

For me I allocate 5Mb-10Mb per user

[Kamkan]

Hi,
How did you arrived that figure? What is the logic behind that?

Thanks in advance

[yxez]

Well, from some statistics that an average process being invoked by
users consume 5Mb memory, and i read somewhere that it can be 1/4 of the physical memory. Then adjust it accordingly as no. of users increases.

[Kamkan]

Hi,
U mean SGA to be set 1/4 of Physical mem? I suppose ideal shd be 65% of Physical mem. Could anyone validate this answer?

Thanks.

[yxez]

I mean the total SGA

[pando]

Hi,
U mean SGA to be set 1/4 of Physical mem? I suppose ideal shd be 65% of Physical mem. Could anyone validate this answer?

Thanks.

I have a server with 48GB physical memory and 6 instances running, dont think the rule you have heard about can be used.

[yxez]

May I know what are the total SGAs you used Pando? If I have
that BIG MEMORY, I think I will start my SGA with 4Gb as baseline then adjust/tune it as I go along. Its just really in my instinct

[Kamkan]

Hi,
Yes Pando. I agree. Is there any ideal way to calculate the mem requirements?

Can anyone help to come out with clear idea?

Thanks,
kam.

[tamilselvan]

There is no perfect rule in allocating memory for SGA, PGA, etc; and it varies system to system.
You need to monitor the processes, collect statistics over period of time, and adjust the memory requirements accordingly.

Tamil