How do I know what is the minimum resource requirement for OLAP 11g?

Question

How do I know for OLAP 11gR1 ...
1. what is the minimum number of CPUs and speed required
2. how much minimum physical memory, SGA, PGA etc. is required?
Regards, Anirban

Answer 1

Hello Anirban,
In summary, since the OLAP option is an option to Oracle Database 11g, Enterprise Edition the minimum requirements in order to run the database would be identical to those necessary to run a "Data Warehousing" type installation. That being said starting up a database is a far cry from actually performing well while accessing and building OLAP Cubes in your Database.
There are lots of things to consider. For example: the complexity of your model; data sparcity; level of aggregation; system load, SLAs, etc..
Lets look at true minimum requirements and then consider what it would take to achieve good performance in your environment
TRUE MINIMUM...
I performed a test in my environment (Oracle Database 11g Release 2 (11.2.0.2.0) on Oracle Enterprise Linux 5.5) using Analytic Workspace Manager 11.2.0.2.0A and found the following minimum settings to work against the OLAPTRAIN schema (You may find it here http://www.oracle.com/technetwork/database/options/olap/index.html). This is a very small schema which we use for demonstration purposes.
I discovered that the database started with a memory_target of only 160m (apparently this is the absolute minimum for my environment). I knew that if the database successfully started that I would be able to query the Cube but maintain it? Running queries against the OLAPTRAIN Sales Cube, despite being slow, worked as anticipated. Next, I performed a maintain operation on the Sales Cube where I had to abort the job because it ran into memory issues at 160m, however, when I increased it to only 180m it did a complete maintain in a reasonable timeframe, albeit slow considering the limited resources.
MINIMUM REQUIREMENTS TO ENSURE REASONABLE PERFORMANCE IN YOUR ENVIRONMENT
Most importantly ensure you have a good cube design
Run a sample set of your data in order to define what "reasonable performance" is for your environment. Create a small representative cube in order to test both build and query performance while collecting and analyzing database statistics through AWR and ADDM. For OLAP option specific queries please take a look at http://wiki.oracle.com/page/OLAP+option+-DBASample+Scripts.
You could creat a view on top of your fact table and use the view to generate your OLAP Cube. This will allow you to test a more manageable amount of data. For example, if you have 10 years of data and want to determine the footprint and resources required in order to manage a Cube of this volume then consider scoping it down to a few months first then increase it by a measured amount in order to predict requirements. Monitor your resources and ensure you balance I/O, memory and processors. Since the OLAP option is a Enterprise Edition option it falls under Data Warehousing. As such there is plenty of literature available on oracle.com in order to define what it takes to achieve a balanced Data Warehouse.
I would recommend contacting Oracle Consulting or an Oracle Partner to determine the best fit for your environment.