Topic Last Modified: 2007-01-17

The Microsoft® Exchange Server Analyzer Tool queries the Win32_Directory Microsoft Windows® Management Instrumentation (WMI) class to determine the value of the Compressed key for the message tracking log file path. If the Exchange Server Analyzer determines that the value for the Compressed key is True, an error is displayed.

When message tracking is enabled on an Exchange 2000 Server or an Exchange Server 2003 computer, the tracking logs are written to the following default location:

<drive> :\Program Files\Exchsrvr\ ServerName .log

where <drive> is the drive containing the \Program Files\Exchsrvr path and ServerName is the host name of the Exchange Server computer.

Microsoft does not support the storage of Exchange data files on an NTFS compressed volume. When you store your Exchange data files on a compressed volume, the additional overhead significantly impacts the performance of Exchange. In addition, after an information store database reaches a certain size, approximately 4 gigabytes (GB), it may fail to mount or it may become corrupted.

The Exchange data files include all the following files:

• .edb files
  
  
• .stm files
  
  
• .log files
  
  
• .dat files
  
  
• .eml files
  
  
• .chk files
  
  

Files that are managed by Extensible Storage Engine (ESE) are not designed to be stored on a compressed drive. The ESE depends on sector independence for log-based recovery, and compression of files invalidates sector independence. Compression should not be turned on for volumes hosting ESE databases or any database that uses write-ahead logging.

Before Exchange 2000 Server Service Pack 3, compressed information store databases were allowed to mount. However, corruption can result in any Exchange 2000 Server information store databases or information store logs that have been compressed by using NTFS compression.

With Exchange 2000 Server Service Pack 3, compressed information store database files of 128 megabytes (MB) or fewer are automatically decompressed. When database files grow to larger than 128 MB, the database does not mount and the error messages are generated in the application log. Exchange 2000 Server Service Pack 3 prevents compressed databases larger than 128 MB from mounting.

To turn off file compression for a specified folder

As an alternative to the preceding procedure, you can move the message tracking log files to a different, uncompressed folder. For more information about moving the message tracking log files, see the following Microsoft Knowledge Base articles:

• 84103, "How to change the location of the message tracking logs in Exchange Server 2003" (http://go.microsoft.com/fwlink/?linkid=3052&kbid=841089)
  
  
• 317700, "How to change the location of the message tracking logs in Exchange 2000 Server" (http://go.microsoft.com/fwlink/?LinkId=3052&kbid=317700)
  
  

For more information about Exchange data files and NTFS compression, see the following Knowledge Base articles:

• 170009, "XADM: NTFS Compressed Volume Causes Store to Fail" (http://go.microsoft.com/fwlink/?linkid=3052&kbid=170009)
  
  
• 327772, "XADM: Database Does Not Mount and You Receive Error 0xfffff05b After You Apply SP3" (http://go.microsoft.com/fwlink/?linkid=3052&kbid=327772)
  
  

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