Content compression is not enabled or content compression is too high on the Microsoft-Server-ActiveSync virtual directory

[This topic is intended to address a specific issue called out by the Exchange Server Analyzer Tool. You should apply it only to systems that have had the Exchange Server Analyzer Tool run against them and are experiencing that specific issue. The Exchange Server Analyzer Tool, available as a free download, remotely collects configuration data from each server in the topology and automatically analyzes the data. The resulting report details important configuration issues, potential problems, and nondefault product settings. By following these recommendations, you can achieve better performance, scalability, reliability, and uptime. For more information about the tool or to download the latest versions, see "Microsoft Exchange Analyzers" at https://go.microsoft.com/fwlink/?linkid=34707.]  

Topic Last Modified: 2010-04-01

The Microsoft Exchange Best Practices Analyzer examines the Internet Information Services (IIS) site that hosts the Microsoft-Server-ActiveSync virtual directory. As part of this examination, the Best Practices Analyzer determines whether content compression is enabled for Exchange ActiveSync.

If content compression is enabled, the Best Practices Analyzer retrieves the compression level that is used from the IIS 6 metabase. If content compression is not enabled or if content compression is set too high, the Best Practices Analyzer generates one of the following messages:

If content compression is not enabled

If content compression is set too high

Exchange ActiveSync is a protocol that Exchange uses to synchronize mailboxes with mobile devices. This protocol is optimized to work over high-latency or low-bandwidth connections. Also, this protocol is designed for client computers that have lower amounts of memory, storage capacity, and processing power.

By using content compression, Exchange can optimize the amount of data that is sent between IIS and a mobile device. However, if the content compression level is set too high, the mobile device must perform additional work to uncompress the data. Therefore, the battery life on the device may be reduced.

To address this issue, modify the IIS metabase to set the content compression to a value of 3 or less.

To enable content compression on the Microsoft-Server-ActiveSync virtual directory

1. Start the Exchange Management Shell.

2. At the shell prompt, run the following cmdlet.

   Set-ActiveSyncVirtualDirectory -Identity "contoso\microsoft-server-activesync" -CompressionEnabled:$true
   

To set content compression in the IIS metabase

1. Start the Internet Information Services (IIS) Manager MMC snap-in.

2. Right-click the computer object, point to All Tasks, and then click Backup/Restore Configuration.

3. Click Create Backup, type a name for the backup in the Configuration backup name box, click OK, and then click Close.

4. Right-click the computer, and then click Properties.

5. Click to select the Enable Direct Metabase Edit check box, and then click OK.

6. Start the IIS Metabase Explorer tool. To obtain this tool, see Internet Information Services (IIS) 6.0 Resource Kit Tools.

7. Expand the following path:

   • LM

   • W3SVC

   • Filters

   • Compression

8. Under Compression, click deflate.

9. In the details pane, modify the HcDynamicCompressionLevel parameter to set the level to 3 or less. This parameter may contain values from 0 (minimum compression) through 10 (maximum compression). To modify the value, right-click HcDynamicCompressionLevel, and then click Properties. Click the appropriate value, and then click OK.

10. Under Compression, click gzip.

11. In the details pane, modify the HcDynamicCompressionLevel parameter to set the level to 3 or less.

12. Exit IIS Metabase Explorer.

13. Reset IIS. To do this, run the iisreset /noforce command at a command prompt.

14. In the Internet Information Services (IIS) Manager snap-in, right-click the computer, click Properties, and then click to clear the Enable Direct Metabase Edit check box.