Windows 64-bit in the Enterprise

There are so many good arguments for using a 64-bit OS instead of a 32-bit OS. Since yesterday x64 support for Windows Professional, Standard, Enterprise and Datacenter Server is officially available. Today one of my colleagues did a presentation at WinHEC about Microsoft.com and the transition of our website to 64-bit on x64. Microsoft.com is 100% on 64-bit.

Here's some core information:
On the x86 servers the overall CPU utilization was at about 65%.  Also, there are three distinct CPU spikes where the processors were running at or near 100% for a sustained period of time.  In each case one of the IIS application pools recycled because it had reached its virtual memory limit (sometimes in less than 20 minutes).  On the x64 servers, even for 32-bit processes, there is no application pool recycling anymore because of the larger, up to 4GB, address space it’s enjoying under WoW64.

CPU utilization was typically our main bottleneck on Microsoft.com. Moving to 64-bit we gained ~30%.  While this might not be the case for any application in any scenario, for us this translates into a ~30% less servers we need to run Microsoft.com, translating to reduced manageability cost and less resources overall: A better TCO through 64-bit.

How did all this start? In the beginning the Microsoft.com team started buying x64 hardware to run 32-bit Windows. Once tests with early builds of the OS showed Windows was stable enough, the first 32-bit servers were replaced by 64-bit Windows (one the same hardware!). The 64-bit systems were deployed into production in a pure 32-bit environment. 32-bit and 64-bit Windows are “too compatible” to cause any trouble or issues caused by mixed deployments.

Next step was the deployment of 32-bit components on the 64-bit platforms. Again, 32-bit processes perform well on 64-bit and most applications see immediate benefit of running on a 64-bit OS. Windows has way more headroom on the 64-bit platform to support way more concurrent users, serve more requests due to larger buffer and cache sizes. 32-bit processes are supported by a functionality called Wow64 (Windows-on-Windows 64-bit). Each 32-bit process has access to up to 4GB on a 64-bit Windows. Another tremendous benefit, translating immediately into performance gain on the 64-bit Windows platform.

Should you be looking for more information about Windows on 64-bit, please visit the 2 main landing pages: 64-bit on MS.COM, XP on MS.COM and 64-bit on MSDN for developer.