Source: Walter Eikenboom

While testing and playing around with SCOM 2007 for a few weeks in my test environment my c:\ drive was filling up. Normally there would be a lot of service packs, install and update files on the drive but this time it was clean.

After some searching i found a logfile directory of 2GB in the "C:\Program Files\Microsoft SQL Server\MSSQL.2\Reporting Services\Logfiles" so there was my problem. From the " SQL Server Management studio" there was no possibility to change the location so i had to change de location of the logfiles the following way:
In Notepad, open the ReportingServicesService.exe.config file that is located in the following folder:

Drive:\Program Files\Microsoft SQL Server\MSSQL.x\Reporting Services\ReportServer\Bin
add the following code to the <RStrace> section: 
   <add name="FileName" value="ReportServer_" /> 
   <add name="Directory" value="YourPath" />
In Notepad, open the Web.config file that is located in the following folder: 
   Drive:\Program Files\Microsoft SQL Server\MSSQL.x\Reporting Services\ReportServer 
   Add the code that is listed in step 2 to the Web.config file. 
   In Notepad, open the Web.config file that is located in the following folder: 
   Drive:\Program Files\Microsoft SQL Server\MSSQL.x\Reporting Services\ReportManager 
   Add the code that is listed in step 2 to the Web.config file. 
   Set the same permissions on the new logfile folder as there where on the old logfile folder and restart the ReportServer Windows Service. After moving the old logfiles to the new location the drive space problem was solved.