Restrict Windows CBS.log verbosity, set log level, stop hectomegabyte info madness

As a partial answer here's the setting to stop logging altogether: in the registry, navigate to

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Component Based Servicing]

and set EnableLog 0. Source: https://technet.microsoft.com/en-us/library/cc732334%28v=ws.10%29.aspx#CBS

CBS log is also filled by cleanmgr with roughly 150-200Mb of data even while cleaning almost 'nothing', thus filling op your disk in stead of cleaning.

I found CBS log can be cleared after stopping the TrustedInstaller service, restarting the Windows Module Installer afterwards will start the service again. Bear in mind the log is used by Microsoft in some debugging programs.