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Achieve 99.999% Uptime
Use Windows Server 2003 Datacenter Edition to obtain the highest levels of availability and performance.
by Danielle Ruest and Nelson Ruest

October 4, 2004

For This Solution: Windows Server 2003, Datacenter Edition, Windows Server System, Specialized Hardware

The five nines. In the industry, this means 99.999 percent availability for a service, which translates to less than 5 minutes, 15 seconds of downtime per year. That's a little more than 26 seconds per month or less than 7 seconds per week. That's a tall order, but one that is often a core requirement for some of the most advanced Information Technology implementations that run key applications. You wouldn't want your bank to shut down on a regular basis would you? What about the government? What about your own organization? Do you have critical applications that need this level of service? Now comes the $20 million question: Would you try to achieve 99.999 percent uptime on Windows (see Table 1)?

Microsoft believes you can. That's why the company built the least-known member of the Windows Server 2003 family: Datacenter Edition. Datacenter is more than just another edition of Windows. It's a special original equipment manufacturer (OEM) version that is only available as part of a hardware and software bundle that basically puts a Windows mainframe class computer into your data center. This is a serious program as is evidenced by the OEM partners Microsoft lined up. These include mainframe heavyweights such as IBM, Fujitsu, HP, and Unisys. And that's just for the 32-bit version of Datacenter. The 64-bit version includes several additional players such Bull, Dell, and NEC (see Resources).

What makes Datacenter more robust than any other version of Windows is the hardware it runs on, along with special tweaks included in the operating system. A 32-bit Windows Datacenter Server can run with up to 32 microprocessors and up to 64 GB of RAM. A 64-bit version boosts that to 64 processors and 512 GB of RAM. To run Datacenter, you'll need a machine capable of supporting a minimum of eight processors, and that's for each single partition you run in your Windows mainframe.

Both the 32-bit and the 64-bit versions support up to eight-node server clusters (see the September article on clusters, and the Non-Uniform Memory Access (NUMA) architectures. NUMA is a process whereby Datacenter can call upon a special memory allocation table called the Static Resource Affinity table that is generated by the hardware it runs on. This table lets Datacenter dynamically allocate memory to the appropriate processes through affinity, letting the operating system run more efficiently. NUMA is also supported by the Enterprise Edition of Windows Server 2003, but it is only in Datacenter hardware that you find direct support for this process.

In addition, Microsoft created the Windows System Resource Monitor. This free add-on to the Datacenter and Enterprise editions of Windows Server lets you control which processors your server can use and how much memory each of the applications running on your server can use. This gives you more control over the overall operation of your mainframe Windows machine.

The Ultimate Virtual Server
The Datacenter mainframe is a single machine that provides partitions, both hardware and software, to run instances of Windows. Each instance must have potential access to the minimum number of processors and a proper hardware configuration. A complete Datacenter Server can run multiple instances of Windows Datacenter Edition, forming clusters through partitions that are supported either by the hardware itself or by the special OEM software that is made available with the hardware. In addition, you can use Microsoft Virtual Server 2005 to run virtual instances of your servers. In fact, Datacenter Server could be the ultimate virtual machine server, letting you manage a completely malleable Windows environment. But, the purpose of moving to Datacenter is to consolidate and reduce administration efforts, so be mindful of the number of partitions you choose to run (see Figure 1).

You'll want to run enough to profit from Datacenter's innate clustering technologies, adding to the availability offered by the special hardware and the operating system itself, and making sure your applications are always up and running. Here, it will be essential to have a good understanding of the compatibility of the various software applications you want to run on each partition. Though OEM partners have their own sources for this, there seems to be no easily located public source for the various combinations of the different Windows Server System products you can and should run in each partition. Table 2 outlines the various services and functionalities available through both Windows Server and the Windows Server System stack along with their affinities for each other. Affinities are based on the product or feature's support for the clustering technologies built into the operating system. It should provide valuable assistance in your decision-making process.