If you set Jenkins.rawBuildsDir to an inappropriate value, such as /nonexistent (a path you cannot even create), Jenkins:

1. Does not warn you in the configuration screen.
2. Fails to create new build records. These are reported as a series of exceptions from Run.execute with adequate diagnostics, but not very gracefully.
3. Silently fails to load build records after a restart. Fixed earlier as: https://github.com/jenkinsci/jenkins/commit/a516ade0fe668fb37443206a14381d7efcf0b83b
4. Silently shows an empty console, missing changelog, etc. when displaying the build later. (Unlike #2/#3, there is no diagnostic if you have changed the build root within a Jenkins session after running a build.)