Topic Last Modified: 2007-03-23
The Microsoft Exchange Analyzer tool queries the Active Directory directory service to determine the value configured for the msExchESEParamCircularLog attribute.
A value of 1 for the msExchESEParamCircularLog attribute indicates that circular logging is enabled. A value of 0 for the msExchESEParamCircularLog attribute indicates that circular logging is disabled.
The Exchange Analyzer also determines whether the following conditions are present:
- Exchange Server is configured as a front-end server.
- The SMTP service is running and determines how many mailboxes
If the Exchange Analyzer finds the following conditions are present, the Exchange Analyzer displays a warning:
- The msExchESEParamCircularLog attribute is configured
with a value of 0.
- The server is not configured as a front-end server.
- Fewer than 20 mailboxes are configured.
In the standard transaction logging that is used by Exchange Server, each database transaction in a storage group is written to a log file, and then each database transaction is written to the database. When a log file reaches a certain size, it is renamed, and a new log file is created. Over time, this standard transaction logging creates a set of log files. If the system fails, you can recover the transactions by replaying the data from these log files into the database.
Circular logging overwrites and reuses the first log file after the data that it contains has been written to the database. In Exchange Server, circular logging is disabled by default.
|By enabling circular logging, you reduce drive storage space requirements. However, if you do not have complete transaction log files, you cannot recover anything more recent than the last full backup. Therefore, circular logging on production servers that contain mailbox data or public folder data is not recommended.|
On front-end Exchange servers, message routing servers (also called infrastructure servers), and bridgehead servers that do not have user mailboxes or public folders, the only messages that are committed are non-delivery reports (NDRs). Therefore, you do not have to keep the transaction files for these servers. Additionally, you do not have to back up these servers. If you enable circular logging on servers that do not host user mailboxes, you can overwrite the transaction log files, and your transaction log files will never exceed 20 MB of data.To enable circular logging for Exchange 2000 Server and Exchange Server 2003
Open Exchange System Manager.
Expand Servers, and then expand an Exchange server.
Right-click the storage group on which you want to enable circular logging, and select Properties. The storage group properties dialog box will appear.
Select the Enable circular logging check box, and then click OK to save the changes.
Close Exchange System Manager and restart the Microsoft Exchange Information Store service for the change to take effect.
Open Exchange Management Console.
Expand Server Configuration, and then expand the server you want to modify.
Right-click the storage group that you want to change, and then click Properties.
In the Properties dialog box, select the Enable circular logging check box.
Click OK to save the setting.
Close Exchange Management Console and restart the Microsoft Exchange Information Store service for the change to take effect.
The following code is an example of the Set-StorageGroup command that enables circular logging for the MyStorageGroup storage group.
Set-StorageGroup -Identity MyStorageGroup -CircularLoggingEnabled $true
For more information about circular logging, see the following Microsoft Knowledge Base articles:
- 258470, "XADM: How to Modify the Circular Logging Setting"
- 147524, "XADM: How Circular Logging Affects the Use of
Transaction Logs" (http://go.microsoft.com/fwlink/?LinkId=3052&kbid=147524)
- 296788, "Offline Backup and Restoration Procedures for
- 314605, "How to turn on or turn off circular logging in
Exchange 2000 Server and Exchange Server 2003" (http://go.microsoft.com/fwlink/?LinkId=3052&kbid=314605)