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RE: Question about RAC

From: Michael Erwin <>
Date: Mon, 30 Oct 2006 13:31:01 -0600
Message-ID: <>

Hi Alex,  

Logical or Physical partitioning (L-Pars) a single host environment to support multiple RAC instances is logical as long as the host server can provide an extreme fault tolerance they need for HA, specifically think Sun 25k, HP SuperDome, IBM p590 class systems. This strategy allows customers to grow & migrate slightly easier than building a 2 node, then adding 2 nodes in the future. In these environments, each partition acts & is managed as you would multiple hosts.  

Many times this is the case with customers that outsourced IT environment management, i.e. Perot, EDS, IBM, where the customer pays for physical system, not L-Pars. In the past I have seen customers buy the biggest boxes on the planet, and then l-par them into 2 & 4 CPU host boxes since it saved them on the outsourced support, in effect spending $5million, so they wouldn't have to spend an additional $300k per month to support 6 smaller hosts. Then they could change the partition configuration as needed or warranted.  

Having said all of that, what is still illogical is for customers to put multiple related instances on the same physical partition of hosts, i.e. Reporting/OLAP Instance along with the OLTP Instance on the same physical CPU/Memory/Bus partition or host.  

Hopefully, your customer isn't considering the use of VMware or Parallel to partition a single small i86 host for production environments.    

Michael Erwin
Hotsos Enterprises, Ltd.
Hotsos Symposium 2007 / March 4-8
Visit for curriculum and schedule details...

From: on behalf of amonte Sent: Mon 10/30/2006 1:24 PM
Subject: Question about RAC

Hi all  

I have a question about RAC.  

I have implemented a few RAC on a couple of customers. I have always worked with two nodes and a single database, i.e 2 servers and a common database in a shared storage.  

I have a customer who wants to use 2 servers to implement 4 RACs, i.e hacing 4 instances in each server. Has anyone done this sort of implemntation? I am not sure if this is logical or ilogical :-)    



Received on Mon Oct 30 2006 - 13:31:01 CST

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