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kernal parameters for

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Valued Contributor

kernal parameters for

hi everyone,

our environment is l2000/hpux 11.00/mc-sg/autoraid/2proc/4gb RAM/oracle (will be upgraded from 8.1.6)

8.1.7 release requires few kernal parameter changes so, thought i would run through this before i make the changes.

i've also attached the output of kmtune of current setup

1. max_thread_proc has 64 which is the default. will be changing to 400

2.maxdsiz is set to 64mb. will be changing to 300mb. i've seen couple of posts that suggests not to allocate more for this parameter. maxdsiz_64bit seems good to me (1 gb)

3. nflocks is set to 664, i guess this seems to be fine to me.

Will these parameter changes be sufficient for the transistion of 8.1.6 to database.

any suggestions on other parameters ?

Lee Tae-kyung
Regular Advisor

Re: kernal parameters for

HI, Stan

I am sure that the value of SHMMAX is same as the phisical memory size of the system in HPUX system.
In additon, SHMMAX is 4G regardless of the phisical memory size in Solaris and is 2G in AIX.

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.

Good day~~
I think I am a specialist in IT Korea^^. I am a programmer and SE and DBA
Brian Crabtree
Honored Contributor

Re: kernal parameters for

You will also need to increase maxssiz and maxssiz_64bit to 120m or so, and maxtsiz and maxtsiz_64bit to around what maxdsiz is. The _64bit parameters do not matter with the 32 bit version of Oracle, only the 64bit.

Honored Contributor

Re: kernal parameters for

hi stan,

According to the "HP-UX: Quick Start Guide - 8.1.X RDBMS Installation" on metalink, you need to Configure at the least the following Kernel Resources:

shmmax=1073741824 or 0X40000000

If you are installing the 64-bit version of Oracle, you must also increase the kernel parameter MAXDSIZ to 384M or higher in order to prevent an 'out of process memory' error during relinking.

Other kernel parameters are ralative to you operating environment and since you have already been running 8.1.6 it would be good to carry along the current parameters.

Remember that if you other application software running on the same server may also impact on theses kernel parameters.

On my servers (running also the application server 9iAS release1) the settings are follows:

Server 1: (rp5430/hpux 11.11/StorageTek/1proc/4gb RAM/oracle )
shmmax 0XF0000000
shmmni 512
shmseg 64
semmns (SEMMNI*2)
semmni 4096
max_thread_proc 1024
nflocks 4096
maxdsiz 0x40000000
maxdsiz_64bit 0x80000000
maxssiz 0x8000000
maxssiz_64bit 0x40000000
maxtsiz 0x40000000
maxtsiz_64bit 0x40000000

Server 2: (l1000/hpux 11.00/internal disks/1proc/2gb RAM/oracle )
shmmax 4294967295
shmmni 200
shmseg 60
semmns (SEMMNI*2)
semmni 1024
max_thread_proc 1024
nflocks 200
maxdsiz 0X24000000
maxdsiz_64bit 0x40000000
maxssiz 0X08000000
maxssiz_64bit 0x00800000
maxtsiz 0X12000000
maxtsiz_64bit 0x40000000

Hope this help!

Best Regards

No person was ever honoured for what he received. Honour has been the reward for what he gave (clavin coolidge)
Valued Contributor

Re: kernal parameters for

Hi brian,

i'm wondering how maxdsiz, maxssiz and maxtsiz are related. currently, i have 64mb, 8mb and 64mb set respectively. so, on what basis maxssiz and maxtsiz gets set if i had to increase maxdsiz to 300 mb.

Israel Oros
Occasional Contributor

Re: kernal parameters for


Here I'm posting the kernel settings for Oracle 8i in several systems I've implemented:

bufpages 0
dbc_max_pct 40
dbc_min_pct 10
dnlc_hash_locks 512
ksi_alloc_max (NPROC*8)
max_thread_proc 256
maxdsiz 0X0C0000000
maxdsiz_64bit 0X400000000
maxfiles 2048
maxfiles_lim 2048
maxssiz 0X08000000
maxssiz_64bit 0X40000000
maxswapchunks 16384
maxtsiz 0X40000000
maxtsiz_64bit 0X40000000
maxuprc ((NPROC*9)/10)
maxusers 512
maxvgs 20
msgmap (MSGTQL+2)
msgmax 65535
msgmnb 65535
msgmni (NPROC)
msgseg 32767
msgssz 128
msgtql (NPROC*5)
ncallout (NPROC*2)
nfile (15*NPROC+2048)
nflocks (NPROC)
ninode (8*NPROC+2048)
nkthread (((NPROC*7)/4)+16)
nproc 4096
npty 200
nstrpty 60
nstrtel (MAXUSERS)
nswapdev 25
semaem 32767
semmap ((NPROC*5)+2)
semmni 32767
semmns 32767
semmnu (NPROC-4)
semume 64
semvmx 32768
shmmax 0X1000000000
shmmni 512
shmseg 256
timeslice 10
unlockable_mem (MAXUSERS*10)
vps_ceiling 64

Best regards,

Brian Crabtree
Honored Contributor

Re: kernal parameters for

Well, I dont think I can explain in depth what these parameters really do. I can give you the information I know about them.

The maxdsiz parameter is the maximum data segment size. This would seem to be related to the size of the SGA. This needs to be 1g or more depending on your SGA.

The maxssiz parameter is the "maximum size for the stack of a process". I have no idea, all I know is that Oracle recommends that this be greater than 120m.

The maxtsiz parameter is the maximum text segment size. I dont know how this relates, but that it should be 1g or greater.

Hope this helps,

A. Clay Stephenson
Acclaimed Contributor

Re: kernal parameters for

Hi Stan,

You have one setting that can turn your box into an absolute dog. Your timeslice is set to 1; set it to 10 immediately. With a setting of 1, as soon as your box gets slightly loaded, it's going to do context switching and very little else. You will be unable to do any other meaningful tuning until this is corrected.
If it ain't broke, I can fix that.
Valued Contributor

Re: kernal parameters for

foremost, a big thanks to stephenson. good catch!

brian, my understanding of maxdsiz was that the maximum size a process can grow. for instance if you set maxdsiz as 64mb and with sort_area_size as 40mb, then a oracle process (dedicated or shared server processes) would get terminiated with ora-4030 out of process memory error if you do a huge batch process. setting a huge value for maxdsiz makes room for all processess to grow the set limit and think if you have too many processess doing this. memory exhausted...lots of swapping...:-(

so, i don't think its releated to size of sga. correct me if am wrong here.

however, thanks for your suggestions.