So my schoolmate asked me to reformat his computer, not before backing up his father's work data. Medical data of his patients.
He had two hard drives, C: and D: . Easy job, it could be done in four steps:
1- collect all data into c:\backup
2- xcopy /e c:\backup d:
3- format c:
4- move all data from d:\backup back to their original places.

Guess which step did I forget to do?
Yes, step 2.

Lol

this... this is really bad...

I feel like medical data should have backups as is. At worst this should (again should, god knows the security shitstorm that is modern society) be a minor nuisance of having to retrieve client data from a backup.

before you do anything more, dd the entire disk to another that is empty an larger, then run file recovery tools on the copy

@Paramite he had to tell the bad news to his father. I wasn't there then, and I was too ashamed to ask him how it went.

@nikmanG IT knowledge was very little at that time (1998-ish), let alone backup practices.

@raldo94 that's what I'd do now. At that time, I didn't even know the existence of Linux (I started with Mandrake 6). That shit happened with plain MS-DOS command line.
I knew how to undelete individual files (there was a command for that), but recover a format was a different story.
I remember going around computer shops in my town (no internet yet) knowing if anyone knew how to recover from a formatted drive. People were looking at us like we asked how to un-cook an egg.

@redundandundant ok yeah, the date does change things a bit