Database Software

Hello everyone

I am trying to design a database consolidation high-availability cluster for Oracle 11g R2 64-bit Enterprise Edition (X86-64) on Oracle Linux 6.x UEK, using Oracle 11.2.0.3 (the latest as of Aug 2012).

We don't need RAC Multi-Node now or in forseeable future because none of the databases we run break the capacity of a single node.
Likewise, we don't need to use Oracle VM to virtualise the database instances.

We plan to use SGA and PGA memory management to run multiple instances on same hardware operating on a single Linux 64-bit O/S image.

Does it sound ok so far?

Two or three of 4-socket, 40-core Intel 64-bit servers with 512GB of RAM each (relatively cheap at today's HW commodity prices) will be sufficient to run all Oracle databases we have on Linux 64-bit.

So the two HA options that I know of are:

(1) use Oracle Clusterware/Grid/ASM to provide for instance failover
(2) use Oracle RAC One Node on top of Clusterware/Grid/ASM

As I understand it RAC One Node is significantly more expensive than the "free" Oracle Clusterware/ASM/Grid (since we own Oracle 11.2.0.3 Enterprise Licences already).

So why should my employer pay for RAC One Node licence given they already own Single Instance Fail-Over and Restart protection from Clusterware/Grid/ASM ?

I also read that Data Guard 11.2 may not be supported with RAC One Node on 11.2? True?

Will same Data Guard 11.2 work with a Single-Instance Failover running on Clusterware/Grid/ASM ?

Who is running RAC One Node? Why?
Who is running Single Instance Failover with Clusterware? Why?
Who is using Data Guard with either of the above?

Please share your stories.

Many thanks
Yuri B