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Changing data seg size kernal parameter

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Shehan
Super Advisor

Changing data seg size kernal parameter

Hi All

What's the maximum increasing size of "data seg size" kernal parameter in hp-ux 11i v1


Thanks
Nirukshitha
31 REPLIES
Jeeshan
Honored Contributor
Solution

Re: Changing data seg size kernal parameter

Do you mean maxdsiz parameter?

it's depend upon the application's requirement.

for Oracle 9i database it's recommended value is 1GB.
a warrior never quits
Shehan
Super Advisor

Re: Changing data seg size kernal parameter

Hi Ahsan

Yes. Our customer is having Oracle 10g. They want us to change remaining to unlimited. Is it possible ?

Regards
Nirukshitha
Jeeshan
Honored Contributor

Re: Changing data seg size kernal parameter

setting unlimited is not the good way because of further performance measure.

you can increase parameter values according to your need.

also note that, this may impact to other parameters.
a warrior never quits
Shehan
Super Advisor

Re: Changing data seg size kernal parameter

Hi Ahsan

What do you recommend for Oracle 10g?

Regards
Nirukshitha
Jeeshan
Honored Contributor

Re: Changing data seg size kernal parameter

From Oracle documentation recommended value is 1 GB.

but it completely depends upon application's load and it's behavior as i said earlier.
a warrior never quits
Venkatesh BL
Honored Contributor

Re: Changing data seg size kernal parameter

check out the manpage for 'maxdsiz' to understand the max & min values.
Dennis Handly
Acclaimed Contributor

Re: Changing data seg size kernal parameter

You can only increase maxdsiz to 4 Gb. Most applications can't take advantage of over 1 Gb.
You can increase maxdsiz_64bit to much larger for 64 bit apps.
Shehan
Super Advisor

Re: Changing data seg size kernal parameter

Hi Dennis

1) What is different between maxdsiz_64bit and maxdsiz?

2) Do we need to change both Valve ?

3) What's the recommended level of maxdsiz_64bit ?

Regards
Nirukshitha



Jeeshan
Honored Contributor

Re: Changing data seg size kernal parameter

>>1) What is different between maxdsiz_64bit and maxdsiz?

maxdsiz is for 32 bit systems &
maxdsiz_64bit is for 64 bit systems

>>2) Do we need to change both Valve ?

yes, accordingly.

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

you can set this value as twice from maxdsiz.
a warrior never quits
Shehan
Super Advisor

Re: Changing data seg size kernal parameter

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
Acclaimed Contributor

Re: Changing data seg size kernal parameter

>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
Acclaimed Contributor

Re: Changing data seg size kernal parameter

>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
Super Advisor

Re: Changing data seg size kernal parameter

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
Acclaimed Contributor

Re: Changing data seg size kernal parameter

>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
Super Advisor

Re: Changing data seg size kernal parameter

Hi Dennis

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

Regards
Nirukshitha
Dennis Handly
Acclaimed Contributor

Re: Changing data seg size kernal parameter

>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
Super Advisor

Re: Changing data seg size kernal parameter

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
Acclaimed Contributor

Re: Changing data seg size kernal parameter

>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
Super Advisor

Re: Changing data seg size kernal parameter

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
Dennis Handly
Acclaimed Contributor

Re: Changing data seg size kernal parameter

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

Basically Oracle's SGA is taken from shared memory so multiple processes can use it. This is limited by the kernel parm shmmax, not maxdsiz.
Shehan
Super Advisor

Re: Changing data seg size kernal parameter

Hi Dennis

You mean we don't need to change this parameter in order to resolve this issue. is it?

Regards
Nirukshitha
Dennis Handly
Acclaimed Contributor

Re: Changing data seg size kernal parameter

>You mean we don't need to change this parameter in order to resolve this issue. is it?

I don't think I saw your current values for maxdsiz and maxdsiz_64bit??
I would suggest you increase maxdsiz to 1 Gb
and maxdsiz_64bit to 4 Gb, if they aren't already at those values.
Shehan
Super Advisor

Re: Changing data seg size kernal parameter

Hi Dennis

Please see below for the current valves.

maxdsiz 1073741824
maxdsiz_64bit 2147483648

So, please let me know more suitable values.


Regards
Nirukshitha

Venkatesh BL
Honored Contributor

Re: Changing data seg size kernal parameter

Your current maxdsiz_64bit is '2 GB'. The maximum allowed value is '4396972765184' bytes (4GB)