In a recent blog post I wrote as a summary of the goings-on from Oracle OpenWorld this year, I said, "Oracle needs to enable consolidation of multiple applications on Exadata instances to make it more useful." Since that post, Oracle has contacted me stating that they, in fact, do currently enable consolidation of multiple applications within a single Exadata instance. According to Oracle:

"Based on what I am hearing from production customers, I believe that most or more likely all OLTP customers are running more than one application on an Exadata Database Machine in order to get better system utilization. Even the smaller quarter rack is simply too powerful for a single application. XXXX, XXXX, XXXX XXXX, and XXXX are examples of customers having multiple applications on a single Exadata Database Machine. This InformationWeek article, "Oracle Exadata V2 Customer Tells All," discusses how BNP moved 35 applications to an Exadata half rack.

 Note that Exadata is based on proven Oracle RAC technology, which has been used to consolidate multiple applications to a single RAC cluster since 2001. 

We also have customers that are running DW and OLTP on the same Database Machine, including: 

XXXX XXXX – runs DW and OLTP on the same Database Machine “Deployed Oracle Exadata Half Rack to improve data warehousing and online transaction processing, which is essential to factoring interest rates and processing loans.”

XXXX XXXX – moved from two separate servers – one with Oracle for TP and one with Teradata for DW — to a single Exadata Database Machine. Speeds improved 3,000%.

In 2009, XXXX implemented Oracle Exadata after a proof-of-concept revealed that the software improved data processing speed by 3,000%, compared to using a separate database and data warehouse to complete the same function."

So, I stand corrected, it seems that workload consolidation on Exadata is a reality currently. This is important, as in order for users to consider Exadata as a viable alternative to consolidated SAN architectures, it can't create too many hard-to-manage silos. An Exadata environment used as the infrastructure for multiple applications running on Oracle is reasonable. Lots of separate instances of Exadata for each app environment would be much less compelling, but it sounds like this is something that is already viable, and increasingly being deployed by production customers.