Well, when I had to do it again, I unplugged the media drive to foreclose on my own stupidity. Hang on, that's a smart thing to do & therefore doesn't belong on this thread...

Back in the days when hard disks were 14" in diameter, held about 3Mb of extremely vital data and were in a cartridge... the wonderful RK05.

http://www.pdp8.net/rk05/rk05.shtml

There was a headcrash on one of our two drives. We called the engineer. We wern't worried as we had two backups, each on another RK05 cartridge.

The engineer removed the cartridge from the drive, and took one of the backup cartridges and put it in the drive. The damaged head promptly destroyed that disk. So now we were down to one backup. :uhoh:

The engineer took the drive apart, replaced the damaged head, and tested the drive using his own (blank) disk cartridge. The drive was now working perfectly!

He was aware that he'd ****ed up by destroying one of our two backups, so he offered to let us have his disk cartridge as a replacement. We agreed. He then very kindly recreated a second backup for us... at least, he thought he did. Instead, he copied the blank drive over the last remaining backup. :(

I still have the original platter from the first cartridge - it's placed next to a system at work as a permanent reminder of how fragile data is....