Changing data seg size kernal parameter

[Shehan]

Hi Ahsan

1) My system is rp4440 server and running 64 bit HP-UX OS. So do I need to change both of these valves?

2) If I change both of them, is there any harm to the system or other parameters?


Regards
Nirukshitha

[Dennis Handly]

>2) Do we need to change both valves?

You only need to make sure that maxdsiz_64bit >= maxdsiz.

>3) What's the recommended level of maxdsiz_64bit?

It depends on your 64 bit applications. If they are running now, no need to increase them. But if you aren't on 11.23 where it is a dynamic tunable, you might as well increase both in the same reboot.

[Dennis Handly]

>2) If I change both of them, is there any harm to the system or other parameters?

Only if you have an evil application that runs the system out of swapspace. Which will prevent other processes from running and may abort others trying to get more heap space.

[Shehan]

Hi Dennis

1) If the maxdsiz_64bit >= maxdsiz , what will we do then? If not,do we need to increase maxdsiz_64bit to higher valve than maxdsiz?


2) Currently Oracle 10g is running on 64 bit hp-ux 11.11.Hence we will have change both of valves. Isn't it?


Regards
Nirukshitha

[Dennis Handly]

>1) If the maxdsiz_64bit >= maxdsiz, If not, do we need to increase maxdsiz_64bit to higher valve than maxdsiz?

Yes, you need to make sure maxdsiz_64bit >= maxdsiz.

>2) Currently Oracle 10g is running on 64 bit hp-ux 11.11. Hence we will have change both of valves?

All recent HP-UX versions are 64. So it depends if Oracle is 64 bit. You probably only need to change maxdsiz_64bit.

[Shehan]

Hi Dennis

Do you know what the HP recommended maxdsiz? Accordingly we can calculate maxdsize_64bit.

Regards
Nirukshitha

[Dennis Handly]

>Do you know what the HP recommended maxdsiz? Accordingly we can calculate maxdsize_64bit.

It depends on the application. The default maxdsize_64bit is 4 Gb.

[Shehan]

Hi Dennis

As this is 64 bit application, can we go up to maximum level($GB) without any harm to the system?

Regards
Nirukshitha

[Dennis Handly]

>can we go up to maximum level($GB) without any harm to the system?

As I said, evil (poorly written) applications can bring your system to its knees if you make it too big. I would only increase it if you have an application that needs that much heap.
Note: Oracle uses SGA which is taken from shmmax.

[Shehan]

Hi Dennis

I am bit confuse about the "Oracle uses SGA which is taken from shmmax". Appropriate if you can give further idea on that.

Regards
Nirukshitha