Although I know it may appear that the CBS.log is a really verbose log, there are times when you might need for the logging to be more verbose than it already is. Luckily, we have the ability for you to enable verbose logging for CBS. What this adds to the log is the ability to see the files and registry changes happening against an operation. I usually find this particularly helpful when troubleshooting an issue where I think something might be in a specific place (like the registry for example) but I dont know exactly where its happening. At times this verbosity will give me the information I need, and along with solid troubleshooting steps, will allow for me to find and fix the issue.
To enable verbose CBS logging is easy:
1. NET STOP TRUSTEDINSTALLER
2. Add the following system environment variable: WINDOWS_TRACING_FLAGS with a value of 10000. *NOTE: This does not require a reboot to take affect.
3. NET START TRUSTEDINSTALLER
If there is anything new happening that can be logged, it will be. Otherwise, if your logs look the same, you're probably on the wrong path in your troubleshooting.
NOTE: To add a system environment variable do the following:
1. Right click on My Computer and choose Properties
2. Choose the Advanced System settings option
3. Click Environment Variables in the bottom right hand corner of the dialog box
4. Under System Variables choose New and then add the variable name and value
Thanks to Susan for bringing this up :)
Edited to reflect George's comment below on this.