It appears this is a somewhat common issue with SCCM 2012. Basically, the ReportServer LDF file grows to fill all space over time. We've had SCCM running for 4 months, and it hit 65GB in size.

So, if you are either having this issue, or are setting up SCCM 2012 to start with, here are a couple of tips.

1. Switch the backup type to Simple. (SQL Server Management Studio -> Right click on reportserver database -> Properties -> Options ->Recovery Model)
2. Ensure you backup the database.
3. Shrink the LDF file if it doesn't from the backup (DBCC SHRINKFILE(ReportServer_Log,1024) - this will shrink it to 1GB)
4. Limit the LDF file's max size. (SQL Server Management Studio -> Right click on reportserver database -> Properties -> Files -> Click the ... button next to log, change the max size to something sensible. I set it to 2GB here).

Also, another thing to pay attention to is rampant IIS logfile growth. These logs are stored in C:\inetpub\logs\LogFiles. It generates a couple of log files every day, so they build up. You can end up with lots of GB of them. I deal with them using a scheduled task running the following batch file:

Code:
forfiles -p "C:\inetpub\logs\LogFiles\W3SVC1" -s -m *.log /D -30 /C "cmd /c del @path"
forfiles -p "C:\inetpub\logs\LogFiles\W3SVC1313931526" -s -m *.log /D -30 /C "cmd /c del @path"
You may need to alter the paths to the location your log files are stored.