Re: Setting up 10G RAC On a Single Linux Node

premmehrotra_at_hotmail.com wrote in message news:<1112225207.932929.257640_at_z14g2000cwz.googlegroups.com>...
> I have heard some people setup 10G RAC on a single Linux Node for
> learning without using VMWARE.
> There is an article on internet how to do it for Oracle9i but not for
> 10G:
> http://www.polarisdb.com/rac.htm
>
> I am curious how can one set up RAC without simulating two nodes (as
> done with VMWARE). I am not a UNIX or LINUX Administrator but will like
> to know what is the minimum hardware/software required
> for setting up 10G RAC on a single Linux node.
>
> Thanks a lot,

for >
> Prem

I don't usually post here any more, but since someone emailed me specifically to ask me to reply to you, here goes for nothing...

Your curiosity stems from the fact that you have made the same mistake that an awful lot of people have: you've confused RACing with Clustering. RACing simply means opening a database with more than one instance. Clustering means making two servers communicate and cooperate. One has been around for donkey's years and involves hardware, and one has been around (under the name 'RAC' at least) for about 4 years, and only involves software.

Confuse the two, and it's very easy to think that RACing requires a cluster, and hence more than one server (even a virtual one). But if I said to you, "I'm implementing a cluster, is Oracle's RAC compulsory?", you'd laugh at me (I hope), because clusters do far more work around the planet than just run Oracle software.

So: two completely different things. Therefore, of course you can RAC with only one node, provided you can persuade two instances to communicate and cooperate their activities. That requires the installation of some communication software, commonly called the Cluster Management Software, or CMS. And the name is accurate because it happens to be the same software that a hardware cluster uses to get hardware nodes talking to each other: Oracle just hijacks a small part of the communication functionality the CMS provides so that its instances can comunicate with each other.

Trouble is, you can only install that CMS component if the Oracle installer spots a hard disk that is capable of housing a single database that can then be accessed simultaneously by different instances (sensible move, really, on the grounds that the lack of such a hard disk would stop a RAC in its tracks).

So, the long-winded reply to your question is: if you can invent something which looks like a shareable hard disk, then the CMS installer will install, and the presence of the CMS components will persuade the main Oracle Installer then to include the RAC software components in the full Oracle installation.

Yes, VMware allows you to simulate such a hard disk -and by the way, it is absolutely NOT the case that VMware is needed to simulate multiple *nodes*. In my 9i Windows Laptop Rac article (http://www.dizwell.com/html/rac9iwin.html) VMware is used to create ONE node, but a shareable hard disk.

The key, in other words, is the hard disk, not the number of nodes. So if you can create something that looks like a hard disk, and something which looks shareable, then you've got the problem licked. That's what raw is good at, for example -which your Polaris article uses. Raw means no file system getting in the way with its inode locking problems to prevent true simultaneous sharing of the one set of database files amongst instances. In 10g, ASM does the same thing, because ASM is, in one sense, just a logical wrapper around a bunch of raw partitions. Now I've just documented how you can simulate an ASM storage array on a Linux laptop at
http://www.dizwell.com/html/desktop_asm.html. Since that article gives you the first and most crucial step in the task of simulating a RAC, it shouldn't be too hard to work out how to finish the job off... though if you care to wait until the end of April, you'll find an article specifically describing the entire process at www.dizwell.com. Assuming things go according to the planned schedule, anyway!

Minimum hardware required to simulate a two-instance RAC therefore: about 512MB of RAM and 6GB of hard disk space.

HJR
www.dizwell.com

PS. I don't review this group any more, so if you want to discuss the matter further, get me at the Dizwell Forum. Received on Thu Mar 31 2005 - 20:33:01 CST