The majority of this is in project/wikiviewstats/bak at:
231G bck
This seems like historical backups?
drwxr-s--- 5 51359 51359 4096 Apr 22 2014 bck
I do not see the tool running and I also notice there is a wikiviewstats2 on http://www.tools.wmflabs.org/?list
Can we remove this bak folder?