Why Doesn’t A Clone Of My Bootable ubuntu Boot?

[box02-0]

Ubuntu 20.04 on a DELL 7791 Laptop
1tb Internal SATA SSD bootable ubuntu
1tb External SATA SSD plugged into laptop via USBC to Esata Cable

Hi.

I am trying to make a clone of a 1tb Internal SATA SSD bootable ubuntu (sda) onto a 1tb External SATA SSD (sdc).

I boot with Gparted Live, and go into terminal.

sudo dd if=/dev/sda of=/dev/sdc bs=1024 (Took 44 minutes)

F12 on the DELL displays the internal ubuntu as one of the bootable options, but the destination clone does not appear at all.

The destination SSD looks identical to the source, however, it is not bootable. (Both the ubuntu partitions have identical uuid's, as expected.)

How come?

Thanks,
M...

[TheFu]

Cloned disks cannot be connected at the same time after the cloning ends. All the unique UUIDs are cloned too, so they are not unique any more. That's not good.

That's my first guess. There are other possible issues too, but more details would be needed like did you force new uuids and change the fstab to be consistent?

[box02-0]

Cloned disks cannot be connected at the same time after the cloning ends. All he unique UUIDs are cloned too, so they are not unique any more.

That's my first guess. There are other possible issues too, but more details would be needed like dd you force new uuids and change the fstab to be consistent?

Hi.
No I did not touch UUIDs or fstab. I just did the "dd" as above.
M...

[QIII]

The next question was implicit in TheFu's response: did you disconnect the original drive before attempting to boot? Did you alter your BIOS/EFI to attempt to boot first to the cloned drive?

[TheFu]

Hi.
No I did not touch UUIDs or fstab. I just did the "dd" as above.
M...

Well, that's great if you put the drive into a different system. Won't work if both drives are connected to a single system or more correctly, won't work with consistent results.

[HermanAB]

The problem is that if you clone a disk, then the UUIDs of the old disks are also copied in the /etc/fstab and /etc/mtab files, while the UUIDs of the new disks are different. The resulting clone cannot boot, since the system goes looking for the old disk.

Making a clone of a Linux disk is generally a waste of time and disks. It is usually better to only backup your data and when your system fails, install a fresh version of Linux and restore your data.

There is no point in backing up the whole Linux distribution. There are thousands of copies at universities around the world already.

[box02-0]

Hi.

Thanks for all the responses.

Yes I thought duplicate UUID's might be an issue. But I would think that a cloned disk would at least show up as a bootable option when I hit F12 on my DELL. The Internal shows up, but the external does not show at all.

I would never run a system live with 2 identical drives as I know there would be issues with duplicate UUIDs.

When I boot with the GParted USB, I can clearly see both drives which look identical.

Is there a difference because I'm trying to boot via USBC vs the internal drive? I just want to be able to determine that the clone is bootable - not actually boot it.

I have lots of custom software on my ubuntu. Not easy to rebuild from an iso off the internet. As a result, I typically clone drives as a backup. If an internal drive fails, it makes a recovery easy - just plug in the cloned backup and minutes later it's business as usual.

To review - I booted with Gparted, went into terminal, did the "DD clone", booted the DELL with an F12, and did not see the cloned drive as a possible bootable drive.

Thanks,
M....

[rbmorse]

Does the ESP partition on the clone have the boot and ESP flags set? You can check with gparted.

[oldfred]

Just like live installer, external drives boot from /EFI/Boot/bootx64.efi which is an UEFI:USB entry in UEFI boot menu.
Not from an 'ubuntu' entry.
You can create an ubuntu entry, but when drives are disconnected UEFI normally forgets specific entries.
You do have to have ESP - efi system partition as FAT32 with esp/boot flag.

[tea for one]

Have you tried this?

Remove, isolate, de-activate your source SSD
Only leave the cloned disk accessible

Does it boot?