The question is often asked, why is it necessary to use the text log file format w3c, instead of the MSDE format which is the default for Forefront TMG 2010/ISA 2006.
The first reason is directly related to ProxyInspector, the log file processing speed. Text log files are processed much quicker than log files in MSDE/SQL Express databases. The reasons for this are quite clear, MSDE/SQL Express is a simplified version of Microsoft SQL Server, and contains most of its older brother's features (transaction, fault tolerance, etc.). Most SQL server features are not needed at all when working with log files, but they seriously affect productivity. In addition, access to the database is through a special interface (ADO - ActiveX Data Objects) and MS SQL driver, as opposed to reading text log files directly from the disk.
The second reason is the volume that log files take up on the server's disk. MSDE/SQL Express format log files take up to 6-8 times more space than w3c format text log files. In addition, with w3c, unused fields can be switched off, which reduces log file size even more. For example, if the weekly volume of log files in MSDE format is 1000MB, then with w3c format this reduces to about 150MB.
The third reason is TMG/ISA server productivity. It is clear that text log files take much less processing time and reduce the workload of the disk subsystem.
The only disadvantage of using w3c log files is that reports embedded in Forefront TMG 2010/ISA 2006 do not work. However, this is not a serious disadvantage if ProxyInspector is used.