Q: Merging libraries has rendered my back up disk unreadable

I use Aperture for my main photo libraries, and it is currently pretty large, 192 GB or so. I have this library also backed up up on an external disk, but I have recently become very frustrated with first iPhoto and then Photos seeming wanting to import photos from various other devices like phones and iPads so I decided to try and merge all the libraries together and start centralizing things. After reading this article (Aperture 3.3: How to use Aperture to merge iPhoto libraries - Apple Support) I started with merging a 14GB iPhoto library to my current library on hard disk. It seemed to take forever, and activity monitor reported the app as not responding although looking at other things I think it was running, just using up so much of the available resources even activity monitor couldn't run properly.

Anyhow, I left it overnight merging this relatively small library to the Aperture library, and when I check this morning the disk the library is on is no not mounted, and when I try to mount it it s completely unreadable, disk utility reports it as uninitialized, all photo and other data on that disk appears gone for ever.

Has anyone else seen such catastrophic results with this library merge function?

I don't think it is even worth asking if the data can be recovered is it? Just a list of third party apps that might do a lot better than any included apple tools. Another source of annoyance.

I must say this is the latest in an ongoing series of Apple **** ups across the board in my opinion which is making me question why I continue to by their stuff when they are clearly the new Microsoft in terms of shafting customers.