February 24, 2010

Vista SP2 with over 64 GB RAM Consumes 100% of CPU Because of W3wp.exe

A problem which also affected Windows Server 2003

It’s extremely hard, if not even somewhat inconceivable, for users to understand how a computer equipped with in excess of 64 GB of RAM could have performance issues. However, according to Microsoft, Windows Vista and Windows Server 2008 machines can, in fact, deliver extremely poor performance precisely because of the fact that the hardware resources available include more than 64 GB of system memory. Of course, additional factors have to contribute to this exception, which is caused by an Internet Information Services (IIS) 7.0 process labeled W3wp.exe.

“You run Internet Information Services (IIS) 7.0 on a computer that is running Windows Vista or Windows Server 2008. The computer has more than 64 GB RAM. Unexpectedly, the W3wp.exe IIS process consumes 100% of CPU resources. Therefore, the computer experiences low performance,” Microsoft reveals. “This problem occurs because the highest memory address of the kernel mode HTTP driver (Http.sys) is defined as 64GB.”

Obviously, because of the amount of RAM involved, as well as of the IIS 7.0 usage, the issue described above is associated with machines used as servers, rather than home computers. According to Microsoft, customers would have to be running Windows Vista Service Pack 1 (SP1), Windows Vista Service Pack 2 (SP2), Windows Server 2008, or Windows Server 2008 Service Pack 2 (SP2) in order to be affected by this problem. The Redmond company has already produced a hotfix, which is available for download via Microsoft Support.

Customers that have been using Windows to power their servers even ahead of Windows Vista and Windows Server 2008 might have already come across similar performance issues because of the W3wp.exe process. In fact, W3wp.exe has been responsible in the past for high memory usage on Windows Server 2003 computers with Internet Information Services (IIS) 6.0 installed.

In addition, although on Vista it can consume 100% CPU resources, on Windows Server 2003, W3wp stopped at 99%. “On a computer that is running Microsoft Windows Server 2003, the W3wp.exe process consumes up to 99 percent of the CPU resources every several minutes. This problem occurs if the following conditions are true: microsoft Exchange Server 2003 is running on the computer.Microsoft Outlook Web Access (OWA) is installed on the computer. The Front-end server only option is enabled in Exchange Server 2003,” Microsoft explained.

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