Re: Oracle 9.2 RAC on Red Hat AS 2.1 setup question

"Jeremy Smith" <alceste_at_xmission.xmission.com> wrote in message news:b07gli$eqa$1_at_terabinaries.xmission.com...
> >> How much luck (if any) have people had with the shared disk on firewire
> >> drives that Oracle touts on its website? I'm going to be trying in the
> >> next couple of weeks here (hopefully, if the machines arrive) but I'd
be
> >> interested to hear of any success stories.
> >>
> >> For those unfamiliar, it's a bargain-basement way of having a shared
disk
> >> subsystem: two firewire cards, and an IDE drive in an external
enclosure,
> >> and wallah! shared disk.
> > But if you're looking for bargain-basement ways of RACing (which I
assume
> > means this is a home PC job and not a production database) then there's
no
> > need to invest in any hardware at all. Linux and Windows both can be
made to
> > do multi-instance or multi-node RACing, all on a single PC. The results
can
> > be extremely stable, and provide a very full implementation with which
to
> > get familiar with RAC concepts and procedures.
>
> Yeah, but then it's not really a cluster, is it? Not to say it's not
> valuable where it's valuable, but you don't have a physical interconnect
> nor the ability to do real, nasty, hardware things like brown-out the
power
> or put a really lousy NIC into one of the machines.
>

Well, I disagree. It seems to be my day for disagreement, I'm afraid. It *is* a cluster. The paper I'm thinking of shows how to build two totally independent virtual machines on a single PC. Those virtual machines talk to each other, and instances running within each machine coordinate their activites just as they would in 'real life'. That's a definition of a cluster if ever I heard one.

No, there's no physical interconnect, and of course that's important in the real world (though you are likely to find that vendor-specific solutions will be supplied willy-nilly). What are you worried about not being able to practise on the virtual cluster's virtual interconnect that you were hoping to do on a physical one? I'm not aware of vast amounts of day-to-day tweaking of the interconnect in production RACs, so I can't see quite what you feel you'd be missing.

Not in the paper, but perfectly possible is the ability to install two (or more) virtual NICs into each virtual machine. So you can practise configuring public network traffic separate from private instance traffic.

As for nasty brownouts: shutdown one of the virtual machines and see what happens (VMware lets you power off a virtual machine suddenly, or shut it down cleanly). It's as realistic as you'll get when one of your physical nodes decide to have a RAM spasm. Shutdown aborts are functionally identical to loss of power, too, if you fancy just killing off the instance rather than the entire virtual machine.

As for practising with dodgy NICs, it's perfectly possible to disable a virtual one, and again see what happens. Or kill the CMS service (if you're doing the Windows one). See how the cluster behaves then.

I'm not saying that the el-cheapo way of knocking up a "real" cluster that you proposed isn't a good idea, far from it. I was merely pointing out that Mr. Redhouse's faux-RACs are actually a very realistic platform on which to experiment with nearly any aspect of RACing that you are likely to face in a production environment. Setup, software configuration, database configuration, disk partitioning, working with raw partitions, use of a cluster file system, backup and recovery, Enterprise Manager setup, performance tuning (yes, the absolute results are of course dodgy, but the relative stuff is what counts), simulated hardware failure, monitoring interconnect traffic, performing instance recoveries. And so on. And my point was merely that aside from the Windows licenses (and don't mention it, but you can even sidestep that issue if you're not using XP), the whole lot is free, with not a dollar to spend on anything.

It has the side-benefit too of introducing people to VMware, which I've found extremely handy for knocking up all sorts of test environments without completely stuffing up my real PC. Advanced replication between two machines, rather than just two instances. Different versions of Oracle. Data Guard setups. And so on. It's been a boon since I discovered VMware, so it's a good thing to get to know (IMHO). Of course, having a nice firewire drive would also be nice!

Regards
HJR
> And Firewire has RAID enclosures now...
>
> Jer
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> >> Jer Smith
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Received on Thu Jan 16 2003 - 21:20:48 CST