Microsoft KB Archive/820456

= PRB: Request Forwarding Sometimes Does Not Forward Some Requests on Windows Server 2003 when IIS 6 Runs in Worker Process Isolation Mode =

Article ID: 820456

Article Last Modified on 12/3/2007

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APPLIES TO


 * Microsoft Application Center 2000 Service Pack 2
 * Microsoft Internet Information Services 6.0
 * Microsoft Windows XP Professional for Itanium-based systems
 * Microsoft Windows Server 2003, Enterprise Edition (32-bit x86)
 * Microsoft Windows Server 2003, Standard Edition (32-bit x86)

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SYMPTOMS
When a Microsoft Windows Server 2003-based system is running Microsoft Internet Information Services 6.0 (IIS) in Worker Process Isolation Mode ( WPIM), Microsoft Application Center 2000 request forwarding (RF) may not forward requests for brief periods of time and may then resume functioning.



CAUSE
The ISAPI filter portion of RF requires several seconds to initialize.

When IIS 6.0 is run in WPIM, ISAPI filters are loaded only when a request for a site comes in and a worker process is started. Until the initialization is complete, the RF filter only passes the requests to the local host, although you expect the requests to be forwarded.

If the sites that share the worker process are all inactive for a while, RF will be unloaded. Therefore, the problem may recur when the next request for the site is received.



RESOLUTION
To resolve this problem, set IIS 6 to run in IIS 5.0 isolation mode.



WORKAROUND
To work around this problem, configure the worker processes to not be recycled for all application pools that contain sites that require RF. This will minimize the number of times that the RF filter is loaded.



STATUS
This behavior is by design.

