Re: oracle on VM or non-VM ?!!

These are complex questions to which you will have to find the answers to your own satisfaction. Nothing I say here should be taken as advice on which you base decisions and I do not speak for my employer.

1)
Haven't tested it myself. It stands to reason that running on a hypervisor means your databases will not get all available CPU and there will be a memory and possibly I/O overhead on things like virtual I/O drivers. 2)
I believe Oracle VM license is free, support is chargeable at something like $1000-$3000 per server.

Here, Oracle provide a calculator:

http://www.oracle.com/us/media/calculator/vm/vm-home-2132015.html

3)
VM gives you the ability to relocate services (databases) - so mainly active/passive. RAC is active/active. If you want active/active you want RAC with multiple non-VM servers probably. 4)
If you are considering running multiple RAC instances inside a single VM on a single server, you are probably making a mistake. (You can run VMs across multiple servers, but that is again active/passive, you can't have non-RAC instances running the same database, and you can't have continuous availability with a single instance even on a VM supported by multiple servers. )

5)
VMWare claim to indemnify you if Oracle come after you for the full estate cost of all the CPU's in your VMWare servers.

In Oracle VM, I think they allow you to partition a server so you allocate only a limited number of CPUs to a database. (I think, or is hard partitioning only available for Exadata?)

You have a lot of research to do. If you have high performance requirements, consider why you would allocate some of your expensively licensed CPU to running the hypervisor, not the database workload. There might be some deployment advantages, but installation of servers and 11g/12c database software can be scripted and fully automated on bare metal too, so I've not seen a convincing reason to use VM, except in Virtualbox for demo/development purposes.

If you have different compatible workloads from the different databases, you might want to consider 12c Multitenant architecture. Means you can allocate up to all available memory to all the database's SGAs. As long as the databases workloads are not likely to conflict you can run them all on one large piece of tin, and plug them in, upgrading independently. I guess it's essentially Oracle's idea of what VM should be for a database server. The additional license is a killer though.

Disclaimer: this does not constitute formal advice and is my opinion only.

Regards,

John

On Sun, 26 Nov 2017 at 07:33 JP . <jprem_at_outlook.com> wrote:

> Friends,
>
> we want to move all our existing prod oracle databases (around 20
> instance, max db size ~500G) from our old h/w (non-VM) to new ones.
> HA,easy manageability, performance,cost being the key factors considered
> for the new machines , would like to know if VM(type-1) would suit our
> needs.
>
> I was looking for "VM or non-VM" kind of articles (from a license, HA ,
> performance perspective). But could not come to a conclusion. It's a bit
> confusing. Want to clarify with experts here.
>
> 1) Does Oracle on VM (type 1) have notable perf issues ?
> 2) Does license cost (or TCO) increase with VM/Oracle combination ?
> 3) Is RAC on VM widely used ?
> 4) RAC on non-VM or single instance on VM - which is good from a HA
> perspective ?
> 5) If VM is advisable, VMware or Oracle VM - which works best overall ?
>
> Your advice and inputs would be very much helpful. Thanks in advance.
>
> ~ JP ~
>
> --

Regards,

John

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