There is one very critical and universal hardware recommendation I make to anyone deploying database servers, whether virtualized or not, and that is to not enable Hyper-Threading on your servers CPUs. Never do this no matter how much the urge to double your processor count may be. These are really not true CPUs, but rather a technique by which to trick the operating system into thinking there are twice as many processors. In every database benchmark I have ever done or read about, the performance penalty has always been around 20%. The reason is simple; database operations tend to cause a stall and flush of the CPU instruction cache by their I/O intensive nature. And such stalls are the most expensive (i.e. worst) thing for Hyper-Threaded CPUs to process. So avoid it at all costs on all of your database servers!

Not every motherboard and BIOS offers you the same settings to tweak or otherwise optimize the servers performance. Listed below are some guidelines for things to consider possibly setting via the BIOS (depending on your specific business requirements or special technical needs):

• Virtualization Technology = ENABLED

• Virus warning = DISABLED

• CPU level 1 cache = ENABLED

• CPU level 2 cache = ENABLED

• APIC mode = ENABLED

• Hyper-Threading = DISABLED

• HDD S.M.A.R.T. capability = DISABLED

• FSB spread spectrum = DISABLED

• AGP spread spectrum = DISABLED

• System BIOS cacheable = DISABLED

  • Video BIOS cacheable = DISABLED

  • Video BIOS shadowing = DISABLED

  • Video RAM cacheable = DISABLED

  • On board audio = DISABLED

  • On board modem = DISABLED

  • On board 1394 (Firewire) = DISABLED

  • On board serial ports = DISABLED

  • On board parallel ports = DISABLED

  • On board game ports = DISABLED

  • ACPI suspend to RAM = DISABLED

  • PCI/VGA Palette Snoop = DISABLED

Remember, you are configuring a machine to function as a server, and a virtual server at that. So it is very unlikely that you will need anything besides the CPU, memory, I/O and network bandwidths. Therefore, you can disable many BIOS settings. This can improve performance and save power, which are both desirable. Furthermore, some of the above recommended values will also result in a more stable system.

Host OS Selection

Sometimes this critical decision has already been made for you. For example, you might work in an all Windows or all Linux shop, so the choice is clear and simple. Or you might be setting up a laptop/notebook for doing demos, and Windows is still the predominate operating system in general business use. So again, the choice may well have been already been made. Regardless, the steps that follow will pretty much remain the same.

But sometimes you will have an option or alternatives in selecting the hosts operating system, and that too takes just a little thought. Since youre only going to virtualization software (i.e. the hypervisor), then you should not care too much about the host operating system selection. Thus, a simple rule can be used here: what is inexpensive, light-weight and relatively stable?

The answer is Linux. It is free, can take as little as a few hundred megabytes to install and run, and offers quite good reliability these days. Plus, its easy to streamline down to a very bare, high speed installation. Not to mention that working with it is fun!

Now, I am not trying to start a heated political debate or religious war here. Im merely saying that the host OS serves just one purpose and that is being a container to run the hypervisor and clients. The clients then can use whatever operating system under which the application or database works best. So why spend money to purchase a host operating system?

Of course, some system administrators and database administrators may still have a few reservations about Linux and its maturity and/or acceptance. IDC had projected that Linux would be mainstream long before now, even within the mission critical enterprise applications and database space as shown in Figure 1.

Figure 1:  Linux Enters the Mainstream

Furthermore, Gartner has tracked Linux adoption progress and shown that while it has not been quite as optimistic as projected (i.e. there are yet some gaps), it is still well within reach of being considered mainstream by the end of 2007 (see Figure 2). [Linux Marches Toward Mainstream Adoption, Gartner, Scott & Weiss, 2003]

Figure 2:  Linux Adoption Progress

Note one last time that I am not saying that Linux is either superior or preferred. I am simply asking a question:  why should you pay for Windows as the virtual host operating system when you only need that host to run the hypervisor in order to run the virtual clients?

So, say that you do choose Linux for the host operating system. The next logical question might be which distribution to choose. Remember that you are only trying to create a host to run the virtual clients, which then themselves run Oracle. Thus, you do not have to necessarily pick one of the Linux distributions supported by Oracle for running their database (i.e. Red Hat, SuSE, Enterprise Linux, etc). Yet common sense would dictate standardizing on a single distribution to keep overall maintenance costs lower.

And, finally, for those who still prefer Microsoft Windows, just be sure to pick a server version of their operating system products such as Windows 2000 Server or Windows 2003 Server (and preferably 64-bit).

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