I created a live LMDE5 system on a USB pen drive using Rufus and everything was working fine except for a large number of warnings and critical error messages I got from
dmesg. There where some security warnings regarding a CPU vulnerability and many ACPI-related errors which appear to be related to some toxic Microsoft hardware driver politics. But among them, there was also a message
There are differences between boot sector and its backup. This is mostly harmless. Differences: (offset:original/backup) <...long list of entries...> 1) Copy original to backup 2) Copy backup to original 3) No action
with roughly 30-40 lines of entries. If I remember correctly, Linux systems create a working boot sector at the beginning of a disk as well as a backup copy at the end of the disk. After reading the few discussions I could find on this somewhat elusive error, I decided to choose the option of replacing the original with its backup.
Unfortunately, this appears to have been a grave mistake as I'm now getting a
Invalid system disk. Replace disk and strike any key
and the system won't boot. Question:
- What exactly causes such a high number of offsets within the boot sector, especially on a virtually plain-vanilla installation, and what would have been the correct action?
- How can it possibly be, if not for a serious bug, that restoring a proper, system-generated backup - following a system message asserting
This is mostly harmless- bricks the system?
- Most importantly: How to solve this issue so the system will boot again?
Note: I did not get any error referring to a "dirty bit" that appears to get set when a drive is not properly unmounted as discussed here. Also, the USB drive itself is virtually new.