Both the hardware and software vendors are rapidly embracing virtualization. However, database vendors have been a bit slow to the dance. It could be that database vendors and DBAs believe that database tuning requires direct access and control over low level IO subsystems for optimal performance. But if the hardware is say, ten times faster, what does a 10-20% overhead for virtualization matter?
 
Although Oracle's MOSC has some documents which state that Oracle has not yet verified or certified the database for virtual machines, it has been the author's experience that virtualization abstraction does not impede nor complicate database deployment, management or tuning. In fact, it seems to simplify it. The only area that poses some additional questions/issues is backup and recovery. B&R has been complicated far earlier by cheap hardware and hardware technologies such as RAID.
 
The real proof for support lies with the CPU vendors - both Intel and AMD have introduced virtualization support in their newer chip designs. With faster clock speeds and ever growing multi-core chips, resource utilization has become key and most CPUs sit idle much of the time. Thus, server consolidation makes total sense; also, the space and power savings gain result in leaner and greener computing centers. And with the proliferation of computing systems, these savings can be quite substantial. One recent article stated that the power savings alone in one company's experience paid for the entire cost of the reduced space needed. This clearly shows that secondary costs such as these are becoming more mission critical than hardware performance and direct costs. In fact, a 100-year old university told me that they could not upgrade their electrical systems in older buildings for their increasing computing needs. Therefore, power requirements alone were the new primary limiting factor in all future hardware purchase decisions.
 
Given the clear benefits and these leaner and greener trends, I would not bet against virtualization going forward. It's not a luxury but, quite often, a necessity these days. And this will only increase with time.

Why VMware Server? 

So why did this book choose VMware Server? The answer is simple: it's free, works flawlessly, is compatible with their non-free products, and VMware has something like a 70% market share. All that means it is a perfect basis for a book. Not only can you download it for free and use this book's virtual appliance contained on the included DVD, but it's quite likely that your current or future virtualization needs will include some VMware products.

That's not to say that other vendors? products are inferior in any way. In fact, since the other products like Microsoft Virtual PC and Virtual Iron are also free, they are also great candidates. However, VMware's popularity, hands down, makes the book universally more applicable. Note that most concepts or techniques mentioned within this book are similarly universal in nature. This means that they should apply, with minimal changes, to these other virtualization platforms as well.

Future Trends

I don't have a magic crystal ball or I would have made a few million in the market and retired already. But it seems clear that the trend is for increased virtualization at nearly every level.

Back in the mid-1960's and early 1970's, mainframes had sufficient excess CPU capacity that warranted the creation of virtual machines (e.g. IBM's VM - which was the origin of the term hypervisor). Contemporary multi-core CPUs and cheap memory make even today's hungriest applications seem tame. So once again, we have spare or excess hardware capacity - even on lowly notebooks and laptops. It seems that there is as much a need for virtualization today as 40 years ago!

Also, today's database administrators and application developers need to work within ever complex and changing environments. Yet again, virtualization is the easiest way to conquer these challenges. Look for virtualization to become prolific and mainstream technology.

Oracle's Own VM

At Oracle Open World 2007, Oracle shocked quite a few people by announcing their own new virtual machine offering: Oracle VM. Oracle claims that it is up to three times faster than other server virtualization product. Now with their Enterprise Linux, Oracle VM, Oracle database, Automatic Storage Management (ASM), the Oracle Cluster File System (OCFS), Oracle has truly become a robust and comprehensive vendor for database infrastructure. Moreover, with their recent applications space acquisitions, Oracle has become a genuine ?one-stop-shop? for running large, scalable enterprise systems.

This book was already half written when Oracle VM debuted and besides, I really do like VMware. Referring again back to Figure 1, Oracle VM is nothing more than repackaging of the open-source based Xen offering (recently acquired by Citrix). It is just another hyper-visor or para-virtualization solution whose core is based upon a streamlined version of Linux (which is the exact topic of Chapter 3). The Oracle VM User Guide displays its architecture with Figure 4 shown on the next page.

 
This is an excerpt from Oracle on VMWare: Expert tips for database virtualization by Rampant TechPress.