Change kernel parameter values.

[ajyeshB]

HI!
I have HP-UX VWVIHRDQ B.11.31 U ia64 OS. Now I want to tune some kernel parameter value as per SAP NOTE. Paramter are

Recommended Existing
shmmax >=0x40000000000 shmmax 17179869184
shmmni >=4096 shmmni 512
shmseg >=512 shmseg 300
maxfiles_lim>=63488 maxfiles_lim 4096 Default Immed
vx_ninode >=131072 vx_ninode 0 0 Immed
vxfs_ifree_timelag -1 vxfs_ifree_timelag 0 0 Immed
nkthread >=250000 nkthread 10000 10000 Immed

But I have a problem that,
at my system
RAM : 8GB
SWAP : 20GB
Database : Oracle 10.2

So please suggest me can I change the paramter value as per suggestion.
I also attach the same with post.
Thanks
Jayesh

[nightwich]

Hi ajyeshB


I do not understand your problem ??

We do a SAP setup and put all the kernel parameters as SAP note.


Regards.

[Fábio dos Anjos]

Hi ajyeshB,

I can't see any problem by following the SAP Note...

These parameters won't cause any headache ...

Bye.

[Dennis Handly]

>please suggest me can I change the parameter value as per suggestion.

Just invoke kctune(1m):
kctune "shmmax>=0x40000000000"

Parms with ">" need quoting. And remove spaces.

[ajyeshB]

Hello Everybody,
Thanks for reply.
My problem is that,
In My server RAM is 8GB, SWAP space is 20GB
if I set the parameter recommeded by SAP,
can any negative effect on performance or increase the perforamce. Because nowday server performance is down when execute some program which access large amount of data.

I am worried about for this parameter

Recommended Existing
shmmax >=0x40000000000 shmmax 17179869184

and how to set the value 0x40000000000.
Please suggest me.

Thanks
Jayesh

[SoorajCleris]

Hi,

If you think the performance is down, as a sysadmin , kindly avoid suspecting something!!!

Do analysis and find out what is the casue.
If your SAP/application recommended some parameter, they must have suggested your server configuration also.

From manpage.
================

When Should the Value of This Tunable Be Raised?
shmmax should be raised if it is below the maximum and user programs
are attempting to shmget segments larger than the current value, and
receiving an [EINVAL] error message.

What Are the Side Effects of Raising the Value?
The only effect is that user programs can use shmget to get larger
segments.
=============================
Changes to this tunable take effect immediately.
============================
If you still believe and observ some issues, you can change it to the old value.

==========================
Check , what is the current usage at high load. Do you really want to increase that?

# kcusage shmmax
Tunable Usage / Setting
=============================================
shmmax 17868904 / 1073741824
[rx26-207]/


Regards,
Sooraj

[ajyeshB]

hi Sooraj,
Before excuting the program I check the shmmax parameter value it shows 4294967296.
On executibg the program which were uses the CPU 98% the parameter shmmax value shows same value 4294967296.
So please suggest me Which parameter value should be change?

[Dennis Handly]

>server RAM is 8GB, SWAP space is 20GB
>if I set the parameter recommended by SAP, can any negative effect on performance
>shmmax>=0x40000000000 shmmax 17,179,869,184

17 Gb is way to much to set shmmax, if you only have 8 Gb

>how to set the value 0x40000000000.

I already did:
kctune "shmmax>=0x40000000000"

This value is WAY too big. It is 4400 GB!
17 Gb is 0x400000000.

>the shmmax parameter value shows 4294967296.

This is a more reasonable value.

[ajyeshB]

Hi!
I am worried, if I set the recommended value. Will server start or not? or If start then can work properly ?
Beacuse this is the production server.

Please suggest me!

Thansk
Jayesh

[Dennis Handly]

>I am worried, if I set the recommended value.

You appear to have too many zeros in your recommended value.
Also does your recommendation know you only have 8 Gb of memory?

[ajyeshB]

Hi!
Actally this parameter is recommeded by SAP.
In that they not mention How much RAM and SWAP space is required. Only they mention the parameters recommed for the HP-UX 11.31

[ajyeshB]

Dear All
Thanks for support me.
Today, I have change the Kernel parameter.
System performance is improve.


Thanks
Jayesh

[nightwich]

Hi


You should allways assign some points to the answers

Regards