To move log files
1. Start Exchange System Manager.
2. Click Administrative Groups.
Note If Administrative Groups does not appear, it may not be turned on. To turn on Administrative Groups, right-click Exchange Organization in Exchange System Manager, and then click Properties. Click to select the Display Administrative Groups check box.
3. Locate the storage group where you want to change log file paths, right-click the storage group, and then click Properties.
4. Click the General tab, click the Browse button next to the Transaction log location box, and then specify the new drive or folder location for the log files.
for more information check out <a href=”http://support.microsoft.com/kb/821915″>microsofts answer here</a> and you can also check out <a href=”http://www.askTheAdmin.com”>AskTheAdmin here</a>