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Re: Windows Multi-node RAC (VMware)

From: Howard J. Rogers <howardjr2000_at_yahoo.com.au>
Date: Tue, 24 Dec 2002 00:45:28 +1100
Message-ID: <QiEN9.8879$jM5.24819@newsfeeds.bigpond.com>

"Billy Verreynne" <vslabs_at_onwe.co.za> wrote in message news:au73a2$i2v$1_at_ctb-nnrp2.saix.net...
> Howard J. Rogers wrote:
>
> > Billy: you've missed the point on this one.
>
> Nothing new. :-)
>
> I'm out of date when it comes to RAC. I used OPS 7.3 many years ago on a
MPP
> cluster.
>
> > Whilst your description of
> > VMware is perfectly correct, the two-node RAC paper the OP is referring
to
> > simply doesn't work in any networking configuration except the Host-Only
> > one.
>
> Don't understand... an IP is an IP is an IP...

Yeah, but we're dealing with totally non-standard, non-certified implementations of some fairly exotic configurations here. And I guess we're at the mercy of VMware and how it does its stuff.

>
> > You are correct that this isn't an issue with RAC itself. But it's most
> > definitely an issue with the test RAC setup (ie, on a single Windows PC)
> > that the paper referred to is creating.
> >
> > And there's no way around it.
>
> Now I'm confused.
>
> I assume that you run two VM's each with RAC on 1 host system. Surely all
> you need to do is configure the two RAC instances with the other node's IP
> address, install RAC in each VM and configure it, right?

Uh huh. I wish!!!

No, 'fraid not. There's something about bridged networking which means that the two nodes don't communicate with each other properly.

>
> BTW, what mechanism does RAC use these days for global pinging? In the old
> OPS days we had to run special software (from the Unix vendor) to provide
> this mechanism. Is this part of the problem with running it under VMware
> and using the virtual IP devices?
>

Well, the paper in question is for Windows. Oracle gave up waiting for Microsoft to deliver proper Cluster Management Software, and thus provides its own. But no, on a Unix environment, we still expect the vendor to supply the clustering software, at which point the RAC install merely puts a small component in place that passes instance-specific messages across the interconnect, whose basic infrastructure is provided by that vendor specific software. In such environments, we refer to Oracle's CMS as a 'message passing conduit', indicating that all it does is pass instance messages from one node to another (basically, the stuff that's responsible for updating the Global Resource Directory, concerning block locks and states).

And I just want to clarify: it makes not a jot of difference to multi-Node RAC whether you specify fixed IP addresses or whether you make use of the cirtual DHCP server that VMware supplies. It simply doesn't work with anything other than host-only networking. God knows why, but that's the way it is.

> Do you have a URL for that paper? I did a quick search on "RAC VMWARE" and
> did not find anything at http://www.oaktable.net (not a member either)

I don't think you need to be a member (but I could be wrong). It's just www.oaktable.net and then click the Files link.

There are two of them: one on single-node-multi-instance-RAC (easy) and one on multi-node-single-instance-per-node-RAC (much, much harder).

(incidentally, the single-node-multi-instance version works just fine and dandy with bridged networking. The multi-node version doesn't).

Regards
HJR
>
>
> --
> Billy
Received on Mon Dec 23 2002 - 07:45:28 CST

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