Re: Real Application Cluster (RAC)

From: Robert Heinzmann <Robert.Heinzmann_at_gmx.net>
Date: Sun, 01 Jun 2003 02:29:51 +0200
Message-ID: <bbbh99$l4s$1@rks1.urz.tu-dresden.de>

Hello,

I'm sorry, maybe I didnt explain my situation well enougth.

Hans Forbrich wrote:
> Robert Heinzmann wrote:
>
>

>>Hello,
>>
>>How transparent is access to a Oracle RAC server group, or so called
>>Cluster ?

>
>
> Depends on the client installation. You can make it almost totally
> transparent to the client (= user) if you set up the client (=software at
> the user's computer) properly. Check out the additional information on
> TAF - transparent applciation failover.
Well, certainly I have a totally messed up view of the problem :). I see it that way :

We have two ways of connecting to a oracle server :

Directly with a native interface
throught some kind of oracle supplied client software

In the b) case, there is actually no problem. you configure the tnsnames.ora acording to the documentation in the "Real Application Clusters Concepts" Part 9 and you have the higher availability.

In case a) (if that is possible, which I dont know , because I'm actually not an oracle user, but just a technician dealing with HA software) the clients have to be aware of the "failover installation" in case of a RAC cluster.

actually my question comes down to :

Do all client services use tnsnames.ora for client connectivity and thus use the HA feature of TAF ?

>
>

>>AFAIK (reading the quite bad documentation) the clients have to know
>>that the Oracle server they connect to is a Oracle RAC server and that
>>there is a failover node (or more). This configuration is done via the
>>tnsnames.ora file. What about clients except sqlplus ? they dont use
>>tnsnames.ora, or do they ? Now do such use the strengthened ability of
>>the RAC cluster?

>
>
> Minor correction here - all clients that use SQL*Net / Net8 / Oracle Net
> Services use TNSNAMES.ora or another of the TNS name variants such as an
> Oracle Names server. And, IIRC, that means all clients (not just
> SQLPlus), other than some specialized cases of JDBC/RMI.
>
> With all due respect, the questions & comments sound almost like you
> started with the "Real Application Clusters Deployment and Performance" or
> "Real Application Clusters Setup and Configuration" manuals. If true, I
> recommend additonal review "Database Concepts" and "Real Application
> Clusters Concepts", available at
> http://otn.oracle.com/docs/products/oracle9i/doc_library/release2/nav/docindex.htm.
>
> (And yes, there is a technique that needs to be learned to be able to read
> the manuals.)

Well, acually I started with the "Real Application Clusters Concepts" Part 9, which I found in google when looking for for an explaination how oracle deals with the transparent access to the service.

We had some customer questions dealing woth oracle RAC and other HA cluster solutions. The customer wanted a comparision of a cetain produkt with RAC. I was not so familiar with RAC, so I looked for some information and found the mentioned "part 9" :)

generally there are 2 ways to get5 access transperency.

the client know how do deal with it
there are techniques that make shure access transperency is guaranteed (IP Failover with gratitious arp or alike)

So I was confused how oracle RAC/TAF handles this ?

Most of our customers use any kind of software wih oracle as the databas and I dont know how they access Oracle, either by JDBC or Native C++ Interface (if that is possible :) or any other way. So I wanted to make shure if transparent access is guaranteed in any way of client connectivity.

I must say that saying the oracle documention is "BAD" was not ok. Generally oracle documentation is good. Technical enougth to get the information you need but still keeping a kind of "overview" of the whole thing. In this certain case I find the documentation not good. I think it is some kind of "marketing material" not dealing with the real problem and telling peaople what to expect from TAF. Thats why I said that the documentation was bad.

To board it up comes down to this (already asked) question :

Do all client services use tnsnames.ora for client connectivity and thus use the HA feature of TAF ?

I hope this explains it a little bit more.

Thank you for your response,

Robert

p.s. sorry for my bad english, but its quite "late" over here :)

>
Received on Sat May 31 2003 - 19:29:51 CDT

Re: Real Application Cluster (RAC) - Access Transperency