Oracle FAQ Your Portal to the Oracle Knowledge Grid

Home -> Community -> Mailing Lists -> Oracle-L -> RE: RAC (Real Application Clusters)

RE: RAC (Real Application Clusters)

From: Scott <>
Date: Fri, 27 Sep 2002 14:51:35 -0800
Message-ID: <>

Greg, For the most part RAW is still a requirement for RAC. There are more Cluster File system Options now then there where 6 months ago.

Windows/2000 - Oracle now provides a CFS. I believe you can download it from OTN. I don't have NT installed so I can't comment on its reliability or stability.

Linux - Sistina has a CFS at $1000/node, Polyserv has a CFS and Oracle is currently developing a CFS for Linux. Sistina is certified for Oracle9i R1 and R2. I am not sure about Polyserv but I think it is certified. I currently use raw devices on Linux but should be installing Sistina sometime in October.

AIX - has a CFS and it is certified by Oracle. Not sure if this for HACMP or RS6000/SP or both.

HP - I don't think there is a CFS available for HP/UX but their newly acquired Compaq TRU64 and OpenVMS has a CFS. HP is eventually doing away with TRU64 so maybe they will roll this technology into their HP/UX MC cluster software.

Solaris 2.7 and lower you will have to use raw devices.

Solaris 2.8 and greater you can use Veritas DBE/AC 3.5, This package includes the Veritas Cluster Volume Manager, Cluster File System, Oracle Disk Manager (ODM, Formerly known as Quick/IO qio), and thier Cluster Server. This software currently supports Oracle9i R1 and R2. This software configuration is only supported on EMC 8XXX series towers(firmware 5567.35.20 or higher) and the Hitachi HDS 9910 and 9960 series( firmware 01-16-40-00/00 or higher). It also recommended you use JNI controllers. Your disk drives will also have to support SCSI-3 persistent reservations and the PR flag has to be set on the disks. The PR reservations are used for IO fencing in the case of any split-brain conditions. I am currently running RAC R1 and R2 using DBE/AC on SUN E6500's and I have been very impressed with their product. I am also running RAC on SUN e3500's using RAW and I have found that the CFS has made my life much easier.

However if you choose to use shared Oracle homes you can have problems with Oracle's IA. The IA doesn't like to share logs and the other files the IA creates and manages. You will have to create separate homes for the agent or symbolically link these files to local directories on these nodes. TRU64 has Context Dependent Symbolic Link (CDSL) facility to separate the $ORACLE_HOME/network directory from the shared Oracle home installation. This is employed by using a specific keyword in the filename (or a symbolic link) that distinguishes the name of the current member node of the cluster.

The other thing I want to comment on is the RAC is implemented differently on different hardware. This is not true. RAC is implemented the same on all hardware. However there are some options that may implemented based on a particular platform. RAC Guard is an option that was specifically geared towards TRU64. In fact Oracle thought it worked so good they licensed the technology from COMPAQ TRU64 and implemented it in RAC guard II so it is available on all platforms. It is true that some platforms may implement clustering better than other platforms, but this is at the hardware level not necessarily at the Oracle level.

Don't forget SQLNET with TAF. Besides OCI you also have to be able to use SQL*Net and thin drivers do not use either.

Jesse, It's hard to say what questions to ask but if I was just learning the product I would stick to a few basic rules.

If it appears to work like magic ask how they got it to work.
If it sounds to good to be true, ask to have them back it up with facts.
Has anyone done this before?
Can they provide references?

The thing is don't be afraid to ask any question. It is surprising how many people won't ask questions because they think it is stupid but everyone else is thinking the same thing. Also the answer may have information for you to ask another question.

The other thing is that if something is said that you don't understand send it to this list. There is enough talent on this list to know when the smoke is blowing in California and it's not from the forest fires.

One last item. Don't look for RAC to fix your application problems. If your application already has problems RAC won't fix that problem and if your application is not designed to scale then RAC will provide high availability but not scalibility.


Do you Yahoo!?
New DSL Internet Access from SBC & Yahoo!
Please see the official ORACLE-L FAQ:
Author: Scott

Fat City Network Services    -- 858-538-5051
San Diego, California        -- Mailing list and web hosting services
To REMOVE yourself from this mailing list, send an E-Mail message
to: (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).
Received on Fri Sep 27 2002 - 17:51:35 CDT

Original text of this message