wiped disk - no longer bootable

[Volker Wysk]

Zitat von Volker Wysk <post at volker-wysk.de>:

> Hi
>
> The problems pile up. I've wiped the first megabyte of both devices  
> (HDD and SSD), because I got a message on boot which sayed that the  
> disk with a specific ID can't be found. Using "dd if=/dev/zero  
> of=/dev/sda ...". Then installed Ubuntu again, which appeared to  
> succeed. But when booting now, it says that there is no bootable  
> medium.
>
> So I have wiped something which I shouldn't. How do I restore that?  
> It doesn't seem to be something which fdisk does.

It's crazy. I've done this:

sfdisk -d /dev/sda > /tmp/sda.bak
sfdisk /dev/sda < /tmp/sda.bak

And now the system boots again! (It's a fresh KISS Ubuntu 19.04.)

It's from https://www.cyberciti.biz/faq/howto-copy-mbr/ .

The installation of Ubuntu was terribly slow. It hung at the message  
"Hole die Datei ... von ..." ("Downloading(?) file ... of ..."). The  
counter counted up very slowly. Seems like the Ubuntu servers are  
overloaded.

Puzzled,
Volker