There have been several entries with questions about the qnap 219 p, and the repeated answer that this method does not work on its processor.
this was mentioned elsewhere, as a tip from the qnap service hotline; it would have helped me to find it here.
As I was on Raid 1, it was simple to remove one of the HD and connect it to my PC. Windows 7 didn't mount the drive, although it was available in the control panel. This did not stop PhotoRec, which i unpacked to my C: Drive, from recovering the lost data. The instructions at the beginning of this thread in using PhotoRec were very helpful with the necessary guesswork about which sector set, etc.
I was pretty restrictive about the file types, but still came up with > 10.000 files (and counting) - to replace the 50 or so i erroneously deleted. Happy hunting.
In retrospect, being mostly_clueless about system admin, I should never have bought this product. It has many wonderful features i'm too clueless to set up,
and has too many potential pitfalls which endanger my data. I would need a 'dummies' mode with safeguards and more basic explanations of terms and processes.
thanks, everyone, in particular avvidme, for your assistance!