That is extremely helpful, thank you.
I currently have several layers of backup - OneDrive, Weekly ... and monthly offsite in case house burns down. My problem was in clearing down old data for my sons who have left home. I burned some to DVD then deleted a folder everywhere else. Later found that the burn failed :-(
This disc is the insides of a Lacie drive that was unusable under Win 11 ( Lacie software issue with fixed IP address and replacement DNS in router!) so its the last place where the data exists.
Lesson - read a DVD once created to see if the data is really there!!!!!
Again - many thanks for the information - onward we go with a dock.