www.makemkv.com

I made a backup of a bluray disc and ended up with 4 directories: BDMV, CERTIFICATE, KDM, MAKEMKV.

My plan was to backup my optical disk to hard disk in case the original gets scratched, etc. Do I need to keep anything other than the BDMV directory?

In particular, the KDM directory contains a bunch of *.bin files that total a whopping 56.2 GiB, more than the 2-layer disc should be able to hold. The BDMV directory (a reasonable 33.5 GiB) seems to be all I need to create mkv files from one of the playlists, so I am curious what the other 3 directories are for, especially this KDM directory.

I make blu-ray backups all the time. I don't think I've ever had a KDM folder in a backup.

As luck would have it, my guinea pig disc (Ponyo - JP) was a bit of a novelty. I couldn't find anything through searching directly here because "kdm" and "bin" were too short as search terms, but websearch found me these topics:

viewtopic.php?f=1&t=8045&p=131691&hilit=mgvc#p131691

viewtopic.php?f=1&t=8415&p=36181&hilit=mgvc#p36181

From what I can tell, MGVC is pretty rare and only read by a handful of hardware players (Panasonic players in Japan). Most common titles seem to be Ghibli movies; maybe there are others, but I am not sure. So it seems unlikely that any software player would ever go to the trouble of implementing support for this, which means having the bits backed up is only useful if I need to burn a replacement for a damaged disc and I actually own a hardware player supporting MGVC. Quite unlikely, so for my purposes, I'm just not going to keep this directory.