Disk cloning
I had an external SCSI master disk that I used to clone to an identical external SCSI disk because the other SCSI disk would become corrupted. My original Master became corrupted so I used one of the other to good disk to copy back to the master. Unfortunately the new master needs to be able to boot but I don’t know how to make the new master a bootable disk. I do not know anything about Unix commands and have been following a set of instructions that someone made 6 years ago.

I took a known good disk when I got to step 12 I reversed the 6 letter ID names and followed the rest of the instructions. I started the instructions over again and when I get to step 11 and try to log in as root is says that is a non bootable disk.
I am adding the instructions so someone with knowledge about UNIX might be able to make sense of this.

1. Power down the workstation and the external load disk.
2. Replace the external load disk with this disk (clone).
3. Power up this disk (clone).
4. Power up the workstation.
5. When you see the display and the message “Initializing memory” press<STOP A>.
6. At the OK prompt type: setenv use-nvramrc? True
7. At the OK prompt type: show-disks
8. Select drive a by pressing the A key.
9. At the OK prompt type: nvalias clone <CTRL Y>@1,0) (press ctrl y followed by @ followed by 1 followed by comma followed by zero)

10. At the OK prompt type: Boot clone (machine will boot of the clone disk)
11. Log in as root. (Type in Password)
12. In a terminal window type: ./copydisk donotpart c1t1d0 c0t0d0
13. When asked of you would like to modify /etc/vfstab on the target disk? Type Y <return>
14. When asked to enter the new 6 letter disk id for thee target- type c0t0d0 <return>
15. At the # prompt type init 0
16. When the OK prompt appears power down the workstation and the external disk (clone).
17. Replace the external disk (clone) with the external load disk.
18. Power up the external load disk.
19. Power up the workstation.
20. Log in.

See this thread - pay attention to the installboot command.

Step 12. In a terminal window type: ./copydisk donotpart c1t1d0 c0t0d0

See if you can take a look at copydisk - it may have a installboot command in it. I would believe copydisk is a script - check with file command ( # file copydisk ) and post what is in copydisk since it seems to be something you may want to understand.