This article describes the installable file system (IFS), which provides access to the Microsoft Web Storage System that SharePoint Portal Server uses. By default, IFS is not mounted during the installation of SharePoint Portal Server.

You can use IFS access for the following tasks:

• Read-only access to the document library
• Microsoft FrontPage Server Extensions
• Web Storage System development through IFS

If you are a server administrator, you can access the IFS by using Microsoft Windows Explorer on the SharePoint Portal Server computer. SharePoint Portal Server typically maps IFS to network drive M, unless there is already a mapping that uses that drive. Although you can use IFS to view the contents of the Web Storage System that is used by SharePoint Portal Server, this access is read-only.

NOTE: Do not use IFS (network drive M) to create SharePoint Portal Server folders or documents, assign security to folders or documents, or edit properties for folders or documents. SharePoint Portal Server roles and configuration options are available when you use the supported Web folders interface. If you manipulate the IFS security attributes, you may interfere with the roles information associated with SharePoint Portal Server, which results in data loss. Workspace management functions, such as creating document profiles, are also available when you use only the Web folders interface. In addition, do not use Microsoft ActiveX Data Objects (ADO) or OLE DB to configure security on SharePoint Portal Server folders or documents.

SharePoint Portal Server Setup uses drive M during Setup and repair operations. The following issues may occur:

• Drive M is added to the backup exclusion list for Microsoft Windows NT backup. You do not see any drives mounted as "M" under the Windows NT backup utility. Use the backup utility for Windows NT to reset this configuration.
• If there are no free drive letters, the repair option of Setup fails. For the repair option to succeed, you must disconnect another drive.

How to Mount Drive M Temporarily

1. Click Start, point to Programs, point to Accessories, and then click Command Prompt.
2. Type subst M: \\.\backofficestorage, and then press ENTER.
   
   If drive M is already mapped, you can use any available drive letter. If the drive is not displayed after you run this command, restart the server, and then run the command again.

How to Mount Drive M Permanently

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

1. Click Start, and then click Run.
2. Type regedit, and then click OK.
3. Locate and click the following registry key:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\EXIFS\Parameters
4. Click Parameters, and then double-click Drive Letter in the Details pane.
5. In Value data, type M, and then click OK. If drive M is already mapped, you can use any available drive letter.
6. Quit Registry Editor.
7. Restart the server.