Topic Last Modified: 2008-04-08

The Microsoft® Exchange Server Analyzer Tool queries the Active Directory® directory service for the msDS-Other-Settings attribute on each Directory Service object for an Exchange 2007 server to determine if the DisableVLVSupport value is the default of 0.

The DisableVLVSupport value determines whether support for Virtual List View (VLV) searches for Lightweight Directory Access Protocol (LDAP) is enabled.

A virtual list is a GUI technique that is employed when ordered lists containing a large number of entries need to be displayed. When the LDAP protocol is extended to use VLV, a window that contains a small number of visible list entries is drawn. The visible portion of the list can be relocated to different points in the list by means of scrolling, slider bars, and cursor keys as well as PAGE UP and PAGE DOWN keys. The user experience is that the full list can be browsed at will, even though it might contain millions of entries. In fact, the complete list contents are never required at any one time. Rather than retrieve the complete list from wherever it is stored (typically, from disk or a remote server), the server retrieves only the information that is required to display the part of the list that is currently in view on the client.

When you have indexed appropriate attributes to use VLV, you can use Ldp (or other VLV-enabled applications) to retrieve large lists from Active Directory without requiring the server to return the entire contents of the results set (improving response speed) and without requiring the search client to store the results set in memory (improving the speed at which results are listed).

If the Exchange Server Analyzer determines that the DisableVLVSupport value is anything other than the default of 0, the Exchange Server Analyzer displays an error.

If VLV support is disabled, all Outlook Web Access paged searches against a domain controller will fail. This may cause performance degradation for Exchange 2007.

To address this error, re-enable VLV support on the affected server.

To re-enable VLV support

  1. Click Start, click Run, type Adsiedit.msc, and then press ENTER.

  2. In the ADSI Edit tool, expand the Configuration[DomainController] node.

  3. Expand the CN=Configuration,DC=DomainName container.

  4. Expand the CN=Services object.

  5. Expand the CN=Windows NT object.

  6. Right-click the CN=Directory Service object. Click Properties.

  7. In the Attributes list, click msds-Other-Settings. Click Edit.

  8. In the Values list, click any instance of DisableVLVSupport=x where x is not equal to 0, and click Remove.

  9. Click OK twice. Close the ADSI Edit tool.