by Ken Task.
And a comment about this part ...
"All the servers do share $CFG->filedir but not $CFG->dataroot (MoodleData)"
That would make sense ... filedir is where all files uploaded to moodle reside ... regardless of which node. All the other directories in moodledata are caches and sessions ... having those on each node would be faster then.
What about moodledata/temp/backup/? (directories that would be used by the async restore?
'SoS', Ken