I asked this over on the Clonezilla forums but they aren't as active as here. At work, I was trying to determine whether Clonezilla is a good solution for replicating our CentOS production servers but I wanted a harmless test subject first. So I choose a Raspberry Pi SD Card. My method was to use Etcher to make the Raspbian Bootable MicroSD card. I then tested it out on the Pi, set up some simple configurations and then went to back it up with Clonezilla.
I did a full disk backup to another external 1TB HDD formatted as a single ext4 partition. Everything went great. I choose the option to let me choose what to do at the end and then selected shutdown, so everything should have been ejected properly.
Then I stuck in a brand new MicroSD Card to restore my image to that. Same brand and size (Samsung 16GB) . It failed once with a bug where the time kept increasing as my write speeds continuously dropped. I made sure to use the 'verify recoverable' and 'resize to fit disk' option and to check SHA1 sums. The second attempt claimed a success.
However, for some reason both microSD cards no longer boot. Upon inspecting them, they appear fine. I mounted both the /boot and / partitions to my Linux Machine and everything looks fine. I first used `lsblk` and `blkid` to verify the UUIDS in /etc/fstab were fine, so I don't think that's the issue. I ran 'fsck -y' to see if anything was there and it detected that the dirty bit was set and removed that. I attempted to boot both again after than and nothing changed.
I'll continue investigating tomorrow morning, but would anyone have insight into why this might be? Any tips on files to look at that might stop it from being bootable? I'll be honest in saying it doesn't give me confidence in performing this on a production server when it could just make my current HDD/configuration unbootable (we do have backups of all files though, it'll just take me a while).