I recently ran into the error 6398 on a customer machine and was stumped. The error was something along the lines of this (below).
The Execute method of job definition Microsoft.SharePoint.Administration.SPUsageImportJobDefinition (ID [GUID]) threw an exception. More information is included below.
Access to the path ‘C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\15\LOGS’ is denied.
To resolve this, I found the following blog post, which helped me completely resolve my issue. What I really like is his use of showing you what not to do, before showing you how to properly solve the issue.
Many thanks to Thomas Balkeståhl!