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Kernel Parameters and Oracle

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Mike Lynch_4
Occasional Contributor

Kernel Parameters and Oracle

Hi all

I am not sure if this is an Oracle or a HP issue but here goes ...
We are running Oracle 8.1.7 on HPUX 11 and are trying to increase the oracle parameter "processes" from 110 to 220.

Whenever we try to do this the instance won't start. The only error we can see is end-of communication-file error on the command line. The alert log just says "Starting up Oracle Instance.."

It also dumps a core in $ORACLE_HOME/dbs

Having read previous posts here's what I think the relevant parameters are

Below is the output of sar -v 1
HP-UX hprod B.11.00 U 9000/800 03/01/04

10:53:34 text-sz ov proc-sz ov inod-sz ov file-sz ov
10:53:35 N/A N/A 431/1044 0 1340/1340 0 3893/10010 0

Any suggestions ?


T G Manikandan
Honored Contributor

Re: Kernel Parameters and Oracle

The problem is with the kernel,you have to increase the semaphores

Jean-Luc Oudart
Honored Contributor

Re: Kernel Parameters and Oracle

Can you post your kernel parameters ?

fiat lux
T G Manikandan
Honored Contributor

Re: Kernel Parameters and Oracle

Oracle recommends setting semmns the value to
Assume there are three Oracle instances A,B and C with processes 100,200 and 300.

Set to the sum of the PROCESSES parameter for each Oracle database,
adding the largest one twice, then add an additional 10 for each database

SEMMNS = [(A=100) + (B=100)] + [(C=200) * 2] + [(# of instances=3) * 10] = 630
Mike Lynch_4
Occasional Contributor

Re: Kernel Parameters and Oracle

Thanks for the quick replies the values are currently set to
semmni = 150
semmns = 406
Jean-Luc Oudart
Honored Contributor

Re: Kernel Parameters and Oracle

I checked a server with many oracle databases
I have :
semmni 1000
semmns 3076

fiat lux
Geoff Wild
Honored Contributor

Re: Kernel Parameters and Oracle

Here's some info for you:

UNIX Kernel Parameters:

Shared Memory

Use the System Administratorâ s Menu (SAM) to configure the HP-UX kernel with the minimum recommended values.


This setting does not affect how much shared memory is needed or used by Oracle8i or the operating system. It is used only to indicate the maximum allowable size. This setting also does not impact operating system kernel resources.




Semaphores SEMMNI 70

Set the number of semaphore set identifiers in the system. SEMMNI determines the number of semaphore sets which can be created at any one time.

The PROCESSES parameter can be found in each initsid.ora file, located in the $ORACLE_HOME/dbs directory. The

default value of PROCESSES for the preconfigured database created by Oracle Database Configuration Assistant is 50.


Set the number of semaphores in the system to 200. The default value of SEMMNS is 128, which is, in most cases, too low for Oracle.

Threads MAX_THREAD_PROC 256 or more

Set the maximum number of threads per process to 256 or more. The default value
of MAX_THREAD_PROC is 64, which is, in most cases, too low for Oracle.

Note: If any of the kernel parameters above are less than your current values, continue to use the current value. These are the requirements for Oracle8i only. If you have other programs which use shared memory and semaphores, you will need to adjust the values accordingly. Take into account that a system reboot is necessary for kernel changes to take effect when planning for current and future database requirements.

My settings for Oracle 9.2 and 1.5 TB DB for SAP:

maxuprc 800
max_thread_proc 256
nfile 189090
nproc 2560
semmni 520
semmns 1024
shmmax 0x400000000
shmmni 256
shmseg 200

BTW - processes = 400 in initSID.ora

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