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My NUC5CPYH was running Mythbuntu and Myth-TV for several months when the fan died. Intel agreed to replace the unit under warranty. Now I deliberately set up my system to facilitate replacement of faulty parts with minimal disruption to TV services for the family.

The MBR, boot partition, operating system, user spaces, configuration and database were all on a 64GB USB flashdrive. TV media storage, swap space, and tmpfs were all on partitions of a 1TB conventional hard drive:

Filesystem 1K-blocks Used Available Use% Mounted on udev 1961380 0 1961380 0% /dev tmpfs 396336 41220 355116 11% /run /dev/sdb2 59522180 8318284 48157240 15% / tmpfs 1981672 140 1981532 1% /dev/shm tmpfs 5120 4 5116 1% /run/lock tmpfs 1981672 0 1981672 0% /sys/fs/cgroup /dev/sdb1 45355 3458 41898 8% /boot/efi /dev/sda2 38448788 49080 36446584 1% /tmp /dev/sda3 907077056 843873704 17102056 99% /myth tmpfs 396336 8 396328 1% /run/user/1000

When the replacement box arrived - another NUC5CPYH - I plugged the drives and RAM into it, but it would not boot. The BIOS setup recognised the UEFI partition was there and I could select it as the primary boot device, but when it tried to boot it would display No boot device.

I created a bootable live USB stick, booted from it (without problems), and was able to attach the other devices, and after a few attempts was able to get grub installed. The system boots as it should now, straight into the Myth-TV front end as an appliance.

The only problem is now that it will only boot if I leave the bootable live-boot USB in! Firstly, it's an ugly fat thing and it offends me having it hanging out of the front of my neat little NUC box. Secondly, it serves no purpose as the system was operating fine without it before the box got replaced. And thirdly it seems dumb to have an extra point of failure for no good reason. And finally, occasionally I want that USB slot for other purposes!

So my question is really two questions I guess:

  1. Is this because the MBR on the 64GB USB is corrupted?
  2. How can I make the 64GB USB bootable again like it used to was?

All the instructions I could find about creating a live USB involved burning an ISO onto the device, which I absolutely do not want to do.

  • Didn't you have to leave the original 64G drive "hanging out of the front"? – Organic Marble Dec 6 '17 at 13:32
  • Check your /etc/fstab. Your disks are probably mounted by UUID, which is different for your new disk. Run blkid, and adjust the /etc/fstab entries with the PARTUUID= values. Oh, and man lsblk;man uuid;man fstab – waltinator Dec 6 '17 at 14:53
  • @waltinator, I don't want to mount the new device. I want the original devices mounted, which is what I'm getting. I checked blkid against fstab just to double-check and the UUIDs are all correct. The problem is that the BIOS isn't recognising the 64GB device as a bootable USB so the system won't boot unless I keep the extra memory stick in there as well, which I don't want. – Terrible Tadpole Dec 7 '17 at 11:01
  • @OrganicMarble the 64GB drive is a Sandisk Ultrafit nano size drive so it sits nearly flush with the front panel. – Terrible Tadpole Dec 7 '17 at 11:02
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Found it here: USB MBR Damaged

I used install-mbr /dev/sdc

I shut down, removed the unwanted USB stick and rebooted from the original 64GB drive. Thank you for your helps.

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