Topic Last Modified: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool reads the following registry entry to determine if the default time to live for each cached Internet Information Services (IIS) file handle has been modified from the default value of 1,880 seconds (30 minutes):


If the Exchange Server Analyzer finds FileCacheLifeTimeSeconds to be present and configured with an alternate value, a non-default configuration message is displayed.

The FileCacheLifeTimeSeconds value specifies the time to live for cached IIS file handles. File handles are cached to improve performance because cached file handles save the server from performing redundant input/output (I/O) and CPU cycles. Each time the SMTP transport stack on an Exchange Server computer receives a message, it is streamed out to the file system where it waits to be routed to its destination. To write to the file system, the SMTP transport stack obtains a file handle and then passes the message into that handle. Each file handle consumes approximately 2 kilobytes (KB) of paged pool memory. The default number of IIS cache file handles is 800 for every 32 MB.

This registry value is not present by default, because Exchange 2000 Server Service Pack 2 (SP2) and later and Exchange Server 2003 are configured to cache an optimal number of file handles. Exchange Server 2003 dynamically calculates the appropriate settings for SMTP files handles, so these settings are no longer needed. Therefore, before upgrading any Exchange 2000 Server computers with these settings to Exchange Server 2003, you should delete these entries from the registry.

This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore the registry if a problem occurs. For information about how to restore the registry, view the "Restore the Registry" Help topic in Regedit.exe or Regedt32.exe.

To revert to the default configuration

  1. Open a registry editor, such as Regedit.exe or Regedt32.exe.

  2. Navigate to: HKLM\System\CurrentControlSet\Services\Inetinfo\Parameters

  3. In the right-hand pane, delete the FileCacheLifeTimeSeconds value.

  4. Close the registry editor and restart the IIS Admin service for the change to take effect.

Before you edit the registry, and for information about how to edit the registry, read Microsoft Knowledge Base article 256986, "Description of the Microsoft Windows Registry" (