From: http://www.infoworld.com/article/3112358/microsoft-windows/windows-7-log-file-compression-bug-can-fill-up-your-hard-drive.html

This is a known problem with Windows 7, 8, and 2008 R2 (and possibly other versions) where 
accumulated log files grow to an enormous size -- 237GB according to one report. If you 
delete the files, Windows kicks in every 20 minutes or so and starts generating 100MB 
files, continuously, until you run out of hard drive space -- again. The overflow files 
go into your Windows Temp folder, typically C:\Windows\Temp.

However, when the cbs.log reaches a size of 2 GB before that cleanup process compresses it, the file 
is too large to be handled by the makecab.exe utility.  The log file is renamed to 
CbsPersist_date_time.log, but when the makecab process attempts to compress it the process 
fails (but only after consuming some 100 MB under \Windows\Temp).  After this, the cleanup 
process runs repeatedly (approx every 20 minutes in my experience).  The process fails every time, 
and also consumes a new ~ 100 MB in \Windows\Temp before dying.  This is repeated until the system 
runs out of drive space.