by Tim Hunt.
There are two sorts of cache files:
One, small set of files stores the cache configuration in the folder called 'muc'. You want to back those up.
But you don't need to store all the cached data, stored in a folder called 'cache'. It can be re-constructed from the data in the Moodle database.
You can also skip backing up 'localcache', 'temp' and 'trashdir'.