Don't understand why people keep on asking the same questions over and over again rather than performing a search and saving everybody's time.

"we are planning to create our development database tier..."
If the eventual production version will be RAC, it is obvious that any load/performance testing environment should be RAC too.
For Development/unit testing/integration testing/business testing, is there a compelling reason for those environments to be RAC ? [I can think of specific cases, eg UTL_FILE may need access to directories on the clustered file system, but nothing saying "MUST" rather than "NICE"]
If so, is it important to have the same number of nodes ?

When dealing with third party applications you may have to run more than instance per server, Its still better to partiton your server into multiple virtual machines and give each dataabse its own seperate OS.

Multiple databases on a single cluster turns into a real headache as there are multiple resources that are shared between all the databases and you can't realistically control which instance gets what. (CPU and the global interconnect are the two I can think of if an instance want 100% cpu it will just take it same with the interconnect bandwidth).

for Rac the better solutuion is one database (one instance per node) and use services and resource manager to control the applications resource uasage. services can be used to restrict an application to certain nodes, resource managaer can control the applications resource usage on each node.

Can you please clarify "the algorithms for certain operations change from 1 to 2, and 2 to 3 - but beyond three not so much. "
Thanks,

Tom,

We are also planning on moving our existing single instance database into a 2 node (to begin with) cluster running 11g on Netapp NFS technology. But, we also have couple of 3rd party databases and some more home grown databases which we want to move into RAC for scalability reasons and some single instance databases into the same NetApp array.

Do you still recommend one instance per node? Can we virtualization be done on Linux side?

Thanks

Thanks Tom for the hundreds of pages I have reviewed and learned from over the years.

The following is to hopefully save other people some time (and possibly buying the wrong hardware for their purposes).

At this point (Nov 4 2008), RAC is not supported for instances in anything but the global zone of a Sun Solaris machine (of which there is only one per machine).

Ref: Metalink white paper 317257.1

However, using Oracle VM (x86, x86_64 only (Nov 4 2008)), all zones can contain instances that are part of RAC cluster(s). I think it is also possible for some other VMs too.

Hi Tom,

this is a valuable forum for oracle related queries and has often helped me in the past. Here though, I was confused by conflicting information on myoraclesupport and Ask Tom so I raised an SR to clarify. (Allow me to say first though that I am fully aware as I'm sure is everyone what Ask Tom is here to do) Here is an excerpt:

"...informed customer that ASK TOM is not a portal that you can ask it for the support status or the certification for the Oracle products, this portal is to provide advises and help in resolving issue unofficially.

The official support portal for Oracle products is the MyOracleSupport, for this reason we have provided him with the formal answer for his question which is "Yes, it is supported to have more than one RAC DB running on the same set of cluster nodes" and the reference is Note.220970.1"

Is this something that has changed with time?... or when you say "Nope, not at all one machine one host one instance" is this just your view on best practice? Please don't think I'm attempting to play one set of advisors off against the other, I'm just keen to find out on behalf of myself and others considering future architecture what is correct.

I'd be interested to hear your views.

Thanks in advance.

Sloth

Hi Tom,

Currently our development database is in single instance. We are planning to use RAC in UAT/production environment. Is this good idea? Will there any performance issue/overhead?

Is there any compelling reason for development environment to be RAC or just for best practices standard?

Our current database version oracle 11g Release 1.

Regards,
Richard

Thanks Tom for your response. Your answers are awesome as usual. However, I am finding it difficult to convince my Manager. The reason is that the database setup (dev-single instance; production - RAC) was proposed by one of the Senior DBA here and he has very good rapport with my manager. Are there any detailed explanations on your book or from the oracle documentation?

Thanks in advance.
Regards,
Richard

How do you feel about the one database per server/host
in an environment like the Oracle Database Appliance?

It seems this environment is more supportable, stack wise by Oracle, with pay as you grow licensing, grid control configuration, ASM,minimal server/file system administration, etc, is fairly easy to install and manage,
and having more than one database per server would at least be easier to manage vs a home grown solution?
I am not proposing millions of tiny db's, but at least
there could be a few larger, consolidated db's, in a RAC, or RAC One Node configuration that would be easy to manage, and provide a little more flexibility for upgrade issues.
They can even be data guarded to another ODA.

With the 11.2.0.3 release for ODA, multiple homes are now supported, so migrations/upgrades could occur based on what applications can or can't be upgraded.

For smaller organizations that can't afford Exadata or to have many servers licensed based on the cost of Oracle licensing, it seems that the only way to go is many databases on one host/server.

I believe the problem of many db's on one server/host will continue to be a problem in terms of administration/troubleshooting until the licensing structure for Oracle changes. Not all shops can support Oracle's VM and VMWare Oracle licensing is expensive. Alternatives are lpar's on UNIX variants where system admin support is expensive also.

Hi Tom,

Your update just above is most interesting and I applaud your willingness to adjust as things change.

I have a few questions:

- in what configurations is I/O resource management across instances available to us? I was told by an Oracle France rep that it only exists for Exadata.

- Also, is it still true that instance caging only works on background processes? Oracle France didn't like it when I said that.

If I back off my "one host, one instance" stance at work, I want to provide all the caveats I can.

Tom,

Thanks for following up, I appreciate your comments. We are migrating to ODA in the very near future, our loaner is coming in Thursday, can't wait! Wish we could afford Exadata, but in time!

Our goal is to consolidate as many db's as possible on the migration to ODA, and put apps/db's on different ODA's based on SLA's, application performance, data growth, data security issues, etc that we have with our customers.

Looking forward to using RAT and Orion next week to test hypothetical workloads and some real workloads.

Thanks
Rob

For Non Rac databases :
is it still true
o do I support this

nope, not at all. One machine, one host - ONE INSTANCE


Usually on HPUX and SUN machines we have multiple Database instances . We have around 16 to 24 gb memory multiple CPUS to support this

Do you mean with respect to Linux x86 64 bit machines :One machine, one host - ONE INSTANCE ?

That would be a very expensive idea buying new hardware for each database system unless on VM

Sorry, yes ODA is Oracle Database Appliance. Been typing Oracle Database Appliance a lot lately for the purchasing department, got lazy..no broken keyboards..