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Re: Oracle DB and Kernel Parameters

 
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Ketill S. Fenne
New Member

Oracle DB and Kernel Parameters

Hi!

We are running Oracle 8.1.7.3 on a dual processor HP server with 1GB RAM running HP-UX 11.00. I need some help from you experts to tune my kernel parameters.

The server is set to run a single database instance. The database will be used to migrate a lot of data between a set of source and target tables. There will only be one database user logged in, and the database will do mostly large inserts / updates with some simple processing.

I am fairly new to HP-UX kernel tuning, and have attached my kernel parameters file.

I believe my database is fairly well-tuned, and we are running a similar windows server with the same database setup which is running the migration around 40% faster...

Best regards
Ketill
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monasingh_1
Trusted Contributor
Solution

Re: Oracle DB and Kernel Parameters

well, kernel parameters do help but I think not in the tune of 40% or so. There is definitely something else mismatched as well.
I would look at followings:

01. Disk setup, lv setup, stripping, mirroring
If you have two channels try to balance load among them, use half the disks on one and rest on other, and then use alternate link. So that you utilize both or more channels.

If you have EMC, ask them to see how is their cache utilization. EMC is not very fast on sequential writting with low cache memory.

Disk subsystem may play a significant role in slowing down things.

02. For local disks, mirroring will help read faster but then may impede you with writting if you do a lot of write. Set the mirro_write_consistence to no.

03. Use 64k size stripping and stripe across many number of disks. BUT, if you use EMC then you may be adding hyndreds of seeks unnecesarily by doing stripping, in that case do not use stripping. Very important factor but purely depends what kind of disk subsystem you use.

04. Filesystem block and fragment size and oracle block size.

05. Are you using raw on one of the server while other one has filesystem?

06. Filesystem setup, you can use various VXFS f/s settings, man newfs_vxfs

07. See the swap utilization, If it is heavy then you will need more memory.

08. See the SGA size. Check the various buffers utilization and re-tune them on HP if needed, if I am not comfortable with that I take help of DBA. You may need to tune the oracle little differently on HP than WINNT.

09. Check the SQL statement of their selection patern to update tables. You may need to tune them.

10. Any trigger or something like that is enabled on tables on HP as opposed to WINNT.

11. Check the indexes for all tables. I am just giving this point just in case over a period of time you have better indexing on WINNT and not on HP.

12. do the statistics update on a regular basis.

13. use glance and see how the system is behaving..

I hope this gives some idea. If you give your database size, volume of updates, may be some one close to that config can provide you with his/her kernel config for more help...
Ravi_8
Honored Contributor

Re: Oracle DB and Kernel Parameters

Hi,

I follow the kernel values given in this URL for 9i, it works fine for all oracle versions till now.

http://otn.oracle.com/docs/products/oracle9i/doc_library/release2/A96167_01/html/pre.htm#CHDCJDHI
never give up
monasingh_1
Trusted Contributor

Re: Oracle DB and Kernel Parameters

Forgot to mention about latest patch bundles, very important..
Steve Steel
Honored Contributor

Re: Oracle DB and Kernel Parameters

Hi


A performance tuning analysis depends on

1)Kernel parameters

2)Patch level

3)Hardware and swap setup

4)Comparison with a windows setup is not really valid .

5)See for help
http://www.ixora.com.au/tips/
http://www.hp.com/solutions1/oracle/
http://docs.cup.hp.com/hpux/onlinedocs/os/11.0/tuningwp.html

Steve Steel
If you want truly to understand something, try to change it. (Kurt Lewin)
Ketill S. Fenne
New Member

Re: Oracle DB and Kernel Parameters

Hi, and thanks for the answers.

My HP - system uses one physical disk, and my Windows system has a c:\ - volume of three mirrored disks, I have tested the disk-speed by copying a 1GB file from one folder to another on the two systems, and they both use about 1 min 30 secs.

"Show sga" returns almost identical figures, total sga is around 20 MB larger on the windows system. (this is because i have a db_block_size=8192 on HP and 4096 on windows)

The windows system has two Intel Pentium 1.3 GHz processor and 1.3 GB RAM, and the HP system (9000/800) has two 650 MHz and 1 GB RAM.

We are doing a lot of Direct Load inserts, and even they are around 40% slower on HP-UX, although the speed of them is almoust directly dependent on disk speed.

Is the difference due to CPU, or does this have to be disk limited

Ketill
Ravi_8
Honored Contributor

Re: Oracle DB and Kernel Parameters

Hi ketill

could you check with Network card, whether it is half or full duplex. we all use Full duplex with Autonegotiatio set to off
never give up
Ketill S. Fenne
New Member

Re: Oracle DB and Kernel Parameters

Hi!

The network card is half duplex with autoneg ON (from SAM).

Will running half duplex impact database performance when all my data and files are on one server?

Ketill
Ravi_8
Honored Contributor

Re: Oracle DB and Kernel Parameters

Hi

Usually it wouldn't. make the network card Full duplex with Autonegotiation OFF, If any serious problem, you can revert back
never give up
Indira Aramandla
Honored Contributor

Re: Oracle DB and Kernel Parameters

Hi,

When you have one instance on the server and only one user will be logged on, and the major processing will be large inserts and updates.

As you databaseis well tuned, please also check the rollback segments and the PCT USED and PCT FREE parameters of the tables into which you would be doing inserts and updates. For frequent inserts the PCT USED parameter whould be 80 to 95. And the proper siging of the rollback segments will not cause "SNAPSHOT TOO OLD" errors.

And if you are using SQL LOADER to load some of the data, use the DIRECT mode for faster load. And if your database is in archivelog mode trun the archive off while loading and then turn it on when completed.

Now comming to the UNIX KERNEL parameter setting for Oracle 8.1.7.3, please refer to the attachment. This describes the parameters for 9i.



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