When the disk that contains the Exchange databases runs out of free disk space, the Microsoft Exchange Information Store service will log an MSExchangeIS 1003 event, and the affected databases will dismount. After this occurs, you may be unable to mount the databases for the affected storage group. This error applies to the following versions of Exchange server:

• Microsoft Exchange Server 2007
  
  
• Microsoft Exchange Server 2003
  
  
• Microsoft Exchange 2000 Server
  
  

To resolve this issue, free some disk space on the database drive, and then try to mount the databases again. To do this, perform one or more of the following:

• If the Exchange database files are the only files that are located on the hard disk, you may have to perform an offline defragmentation of the databases to free disk space.
  
  

  Note:
  Depending on how much free space is available in the database, this step may not resolve your issue.

  For more information about performing this step, see Microsoft Knowledge Base article 328804, How to defragment Exchange databases.
  
  In addition, see How to Run Eseutil /D ( Defragmentation ).
  
  
• If the Exchange transaction log files are also located on this drive, you may be able to free disk space by removing unnecessary log files.
  
  For more information about performing this step, see Microsoft Knowledge Base article 240145, How to remove Exchange Server transaction log files.