PolyBase Bug, or Feature?

I was installing SQL Server software intended for servers on my development machine, as one does, and shouldn't do, when I noticed I had a lot less disk space than I should for a simple install. Well, all right, I can't expect to put server software on my workstation and expect to have that much space left.

Except it got worse. Much, MUCH worse. Within two weeks, I was down to Megabytes. Happened so steadily I didn't notice right away. How did this happen? Did I do something foolish or lazy in my database configuration? Nope.

But I did activate PolyBase.

That was the whole point of the installation, actually. Then I got sidetracked with a more important aspect of the project I needed it for.

At first, I could find no trace of the source of the disk space loss. So I installed a disk tool and found - 360 GBs of log files in a directory I couldn't access, and that said 0kb when I read the properties.

No one could access it. Not a single user. But I did find a way to empty the folder, anyway. Basically, I fooled the system into thinking the files were already deleted by starting the delete as one user, then elevating and deleting as an admin.

At first, I thought maybe I'd installed the program as a non-admin user, but no. I was locked out of the folders as the user who did the install. I'm still trying to come up with a reason why this would be the case, and what caused such massive growth, especially since the cluster had never been configured.

Maybe a peculiarity of installing it to a non-server? Turns out no.

Apparently others have had the same experience. Runaway growth when the feature's not even being used.