Enterprise Kernel/Oracle

Installation and support for Oracle DB on CentOS.
jlegato
Posts: 5
Joined: 2005/01/07 17:40:52
Location: Bethesda, MD USA

Enterprise Kernel/Oracle

Postby jlegato » 2005/01/07 17:51:07

I've installed CentOS on a machine with 6GB of memory. I am running the default kernel:

Linux db3 2.4.21-27.0.1.ELsmp #1 SMP Fri Dec 24 01:28:09 GMT 2004 i686 i686 i386 GNU/Linux

I can correctly see the 6GB of RAM. I've installed Oracle 10g and would like to use a 2.7GB SGA.

The Oracle documention and the howto this howto(http://www.puschitz.com/TuningLinuxForO ... rLargerSGA),refer to a /proc//mapped_base parameter available in
Enterprise kernels. It does not appear to be there when I look at /proc/

I've looked for an enterprise kernel but have had no luck. I see kernel-enterprise packages for CentOS-2

Are they available for CentOS-3.3?

Thanks

John

pmjdebruijn
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Joined: 2005/01/05 15:38:29
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Re: Enterprise Kernel/Oracle

Postby pmjdebruijn » 2005/01/07 19:09:11

I haven't worked with CentOS 2.1 or RHAS 2.1, but I don't think CentOS 3.x has them.

Why because RHEL 3 doesn't have them...

Many many patches were integrated into the RHEL3 kernel. If I'm not mistaken RHEL3 supports up to 64GB using the hugemem kernel.

I don't have any experience working with 1GB+ memory, but I suggest you do some googling for hugetlb(fs).

The link you supplied was dead at the time I tried to view it, but google suggested it was about
Oracle 9g on RHAS 2.1.

I would really suggest to search for another more applicable tutorial.

Regards,
Pascal de Bruijn

jlegato
Posts: 5
Joined: 2005/01/07 17:40:52
Location: Bethesda, MD USA

Re: Enterprise Kernel/Oracle

Postby jlegato » 2005/01/07 19:50:31

Your correct about the removal of the enterprise kernel, The Oracle whitepaper I was reading was
based on AS 2.1. I've looked into hugetlb and may make some use of it. The /proc//mapped_base
deals with moving the location in memory of Oracle's shared libs. It's a patch by Andrea Arcangeli that was
available for some releases up through 2.4.23 (Stock kernel not RH). Red Hat had it in AS 2.1 or so I've
read. I've never used any of RH's commercial releases. I was hoping it was in RHEL AS 3's kernel perhaps
not. I prefer building a standard kernel myself but was willing to use RH's to get the mapped base function.

I may just move to 2.6, I know there is a mapped_base patch for it.

John

jlegato
Posts: 5
Joined: 2005/01/07 17:40:52
Location: Bethesda, MD USA

Re: Enterprise Kernel/Oracle

Postby jlegato » 2005/01/10 15:35:37

It turns out that with RH AS 3 and a kernel with the 4GB/4GB memory split option Oracle allows up
to a 3.6GB SGA without using Very Large Memory(VLM) or moving the shared libs. I've not succeeded
yet but http://www.oracle.com/technology/pub/no ... rhel3.html describes a 3.6GB limit with
the hugemem kernel which I believe turns on the 4GB/4GB split.

John

jlegato
Posts: 5
Joined: 2005/01/07 17:40:52
Location: Bethesda, MD USA

Re: Enterprise Kernel/Oracle

Postby jlegato » 2005/01/11 13:52:05

I've succeded in using a 3.7GB SGA using the hugemem
kernel and loweroing the shared libs address, Doc ID: Note:260152.1 provide instructions the AS3 relinking instructions worked on CentOS 3.3

John

hughesjr
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Enterprise Kernel/Oracle

Postby hughesjr » 2005/01/11 15:16:07

This is great information that I am probably going to use in a couple weeks ... now I won't have to look it up myself :-)

Thanks for posting the results of your research after you fixed your own problem.