Changes to Performance Monitor Web Service Counters in IIS 6.0

Summary

Significant changes have been made to Performance Monitor counters in Internet Information Services ( IIS) 6.0.

This article outlines some of the changes to the Web Service counters .

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Counters That Have New Behavior

Some existing Performance Monitor counters in IIS 6.0 behave differently than they do in Microsoft Internet Information Services ( IIS) 5.0. Understanding these changes will help you interpret Performance Monitor data for IIS 6.0.

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Total Files Sent

In IIS 5.0, when a 404 error ( File not found) is returned, the FilesSent counter is not incremented even if a file was sent with a custom error message. In IIS 6.0, the counter is incremented whether a custom or standard error is returned to the browser.

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Current NonAnonymous Users

In IIS 6.0, Current NonAnonymousUsers are treated as Current Requests; IIS5.0 equates users with connections.

This means that you are going to notice a much smaller CurrentAnonymousUsers count in IIS6 (and therefore a lower MaxAnonymousUser count). The same is true for NonAnonymousUser counters.

In IIS 6.0, CurrentUsers are the number of requests currently being handled by the server. CurrentConnections is a better counter to monitor for scalability and availability (its behavior is unchanged). This number is of course much higher than the number of users for sites that support keep-alive connections. Remember that in IIS6.0, each request (not connection) is considered a user.


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Total Files Sent and Total Files Transferred

IIS 6.0 caches some static files in a kernel-mode device driver named Http.sys. This kernel-mode cache changes the behavior of some counters. You may notice that these counters no longer increment when files are being served out of the kernel-mode cache only:
  • Total Files Sent
  • Total Files Transferred
Instead, the Web service cache counter, Kernel: URI Cache Hits, will be incremented.

Note: Total Anonymous Users and related Anonymous User counters are updated during cache hits. Be aware that the Kernel mode cache does not cache requests that are authenticated. The NonAnonymousUser related counters have not changed.

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Counters Updated by Different Services

Internet Information Services Global counters are now populated by FTP, SMTP, and NNTP services only, so if none of these services are installed (or none are running) the counters in this object will be 0 or not accessible.

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New Counters

IIS 6.0 has three new counters for the Web Service Object:
  • Total Bytes Sent
  • Total Bytes Received
  • Total Bytes Transferred
These provide totals since the start of the Web service.
These are in addition to the counters in IIS 5.0, which provide rate of data transfer:
  • Bytes Received/sec
  • Bytes Sent/sec
  • Bytes Total/sec


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References

More information about Performance Counters in IIS 6.0 and Http.sys is available in the product documentation. To view this documentation, visit the following Microsoft Web sites:

You can also access the product documentation through the IIS Manager. For additional information about how to access this Help feature, click the following article number to view the article in the Microsoft Knowledge Base:
815127 How To: Access IIS 6.0 Help Documentation
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ID do Artigo: 332155 - Última Revisão: 10 de nov de 2008 - Revisão: 1

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