Topic Last Modified: 2007-03-14

The Microsoft Exchange Database Troubleshooter tool detected one or more MSExchangeIS 9518 events with error code 0xfffff743 in the Application log. This indicates that the temporary file namespace for a server has becomes exhausted, or there is no space available to write to the temp folder.


Exchange 2000 Server and Exchange Server 2003 create temporary files in the Temp folder when a large object, such as a message or a file, is streamed into the store and the .stm file is too fragmented to have the entire object written in it.

During normal operation, when the Exchange services are stopped, these files are removed from the Temp folder. If the Exchange server shuts down unexpectedly or the Exchange services terminate unexpectedly, these files are not removed. When the Exchange services are later restarted, new temporary files are created. This results in decreased performance. When the 64,000 temporary file namespace is exhausted, the Exchange services fail to start and the 9518 events with error code 0xfffff743 are logged in the Event Viewer Application log.

User Action

To resolve the issue, do the following:

  • Check the Windows Temp folder for the existence of lb*.tmp files. If these files exist, follow the steps in the following procedure to remove them.

  • Check the drive that hosts the Temp folder for free disk space. If the disk is out of free space, use the following procedure to move the Temp and Tmp folders to a different drive.

To remove the lb*.tmp files from the Windows Temp folder
  1. Click Start, select Programs, select Administrative Tools, and then click Services.

  2. Scroll down to the Microsoft Exchange Information Store.

  3. If the status of the service is Started, right-click the service, and then click Stop

This will disconnect all users from their mailboxes.
  1. Navigate to the %windir%\temp folder, where %windir% is your Windows system root folder, by default this is C:\Windows\Temp.

  2. Delete all lb*.tmp files.

  3. In the Services management console, right-click the Microsoft Exchange Information Store service, and then click Start.

To move the Temp and Tmp folders to a different drive
  1. On the Exchange Server computer, click Start, click Control Panel, and then double-click System.

  2. Click the Advanced tab, and then click Environmental Variables.

  3. Under System Variables, click the line that includes the TEMP variable and the drive, click Edit, and then type the new drive location.

  4. Under System Variables, click the line that includes the TMP variable and the drive, click Edit, and then type the new drive location

Make sure this change is applied to the System Variables and not the User Variables.
If the procedures outlined here do not resolve this issue, consider the information in Microsoft Knowledge Base article 307242, "Information store does not mount with 0xfffff745 and -2235 errors" (

For More Information

For more information about this issue, see the following Microsoft Knowledge Base articles: