Topic Last Modified: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool reads the following registry entry to determine whether the interval for removing unused database indexes has been modified from the default setting:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIS\<ServerName>\Public-<PublicFolderStoreGUID>\Aging Clean Interval

If the Exchange Server Analyzer finds that the Aging Clean Interval key is present and configured, a non-default configuration message is displayed.

One of the functions of the Extensible Storage Engine is to dynamically create indexes when information is resorted or requested in a different sort order. As a result, the Exchange store database could have thousands of indexes on a table. The Exchange store handles this situation by assigning indexes an expiry time. Information about the index is added to an internal table referred to as the index aging table. During online maintenance, the index aging table is reviewed, and each entry’s delete time value is compared to the current time. If the index has expired, the index is removed. By default, this process runs every 24 hours during the Exchange store maintenance cycle and removes entries older than 8 days for Exchange Server 5.5 and 40 days for Exchange 2000 Server and Exchange Server 2003. The Aging Clean Interval key is the interval in milliseconds at which the Exchange store tries to remove indexes. The registry key can be used to override this default and perform this function at a custom interval.

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\MSExchangeIS\<ServerName>\Public-<PublicFolderStoreGUID>

  3. Delete the Aging Clean Interval key.

  4. Close the registry editor.

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

For more information about the Aging Clean Interval key, see the following Knowledge Base articles: