A widely used tool for log file analysis is the open source tool, AWStats. Before setting up AWStats, you will need to make sure Perl installed on your Windows Server 2003/IIS 6 or Windows Server 2008/IIS 7 machine., Three years ago someone added feature to display TB when bandwidth is higher than 1024 GB, but it only added into english lang file and it didn't add into awstats.pl to be default one. In order for you to resolve this issue you need to add message179=TB line in your awstats-pl.txt ., # When AWStats updates its statistics, it stores results of its analysis in # files (AWStats database). All those files are written in the directory # defined by the "DirData" parameter. Set this value to the directory where # you want AWStats to save its database and working files into., Specifies how AWStats statistics are being updated: Disabled: AWStats is disabled. Statistics will not be updated. Static: Static HTML pages will be created after the statistics have been updated. Dynamic: The statistics will be updated, but static pages will not be created. HTML pages will be generated dynamically by the CGI script awstats.pl , There's still a way to tell awstats how the log line is formatted but IIRC it'll miss some fields that will maybe make it not work pretty well. Note that changing Apache logging format will only affect the lines that are logged *after* the change., .