By instruction we were advised to delete all subdirs starts with rec*.

But after this error we discovered, that inside of the "rec-20140209_093232_@" directory there is another one and it is called "factory-@". That is why "btrfs subvolume delete" refused to delete it and we were also advised do not delete "factory-@".

Now questions are:
What "factory-@" is doing inside of "rec-20140209_093232_@"?
How can we delete "rec-20140209_093232_@", if inside there is another directory which we must leave?

thanks in advance