Entries may be logged in the incorrect log file after a new log file is created in Internet Information Services (IIS) 6.0

When you configure logging for a Web site or for an FTP site in Microsoft Internet Information Services (IIS) 6.0, some entries may not be written to the correct log file after a new log file is created. For example, if you specify a log schedule so that a new log file is created every day at 4:00 P.M., an entry for site activity that occurred at 3:59 P.M. may be incorrectly logged in the new log file.

This problem occurs if the following conditions are true:

• The schedule for creating new log files is configured to use one of the following options:
  • Hourly
  • Daily
  • Weekly
  • Monthly
• The Web server is working under a heavy load immediately before the new log file is created. For example, this problem occurs if heavy site activity occurs approximately one second before the new log file is scheduled to be created.

To work around this problem, use one of the following methods:

• Schedule the new log file to be created during a time when less Web site activity or FTP site activity is expected.
• Use the Log Parser tool to open the log files, and then convert the data that the log files contain. With the Log Parser tool, you can create new log files that contain the correct entries or merge the correct entries into the correct log files. Log Parser 2.1 is included in the IIS 6.0 Resource Kit. For more information about the IIS 6.0 Resource Kit, visit the following Microsoft Web site:
  http://www.microsoft.com/downloads/details.aspx?familyid=56FC92EE-A71A-4C73-B628-ADE629C89499&displaylang=en (http://www.microsoft.com/downloads/details.aspx?familyid=56FC92EE-A71A-4C73-B628-ADE629C89499&displaylang=en)
• Use the When file size reaches option. When you use this option, a new log file is created when the current log file reaches the size that you specify. To configure the log schedule to use the When file size reaches option, follow these steps:
  1. Start IIS Manager.
  2. Expand ServerName, expand Web Sites or FTP Sites, right-click the site that you want to configure, and then click Properties.
  3. Click the Web Site tab or the FTP Site tab, and then click Properties.
  4. Under New log schedule, click When file size reaches, specify the log file size that you want in megabytes (MB), and then click OK two times.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

For more information about how to configure logging in IIS, see the "Logging Site Activity" topic in the IIS 6.0 documentation. To view the IIS 6.0 documentation, visit the following Microsoft Web site: