I set up a machine with Debian 12 earlier. The partition schema is fairly standard, except I’m using mdraid for redundancy. I made an image of the two drives, so that I can easily replicate this setup for other machines (I have a bunch of machines that I need to set up in the exact same way.
However, I realized after I finished setting up everything that I chose the wrong pair of disks - instead of the 2.5" SSD pair, I installed it on the NVMe pair which are supposed to be used for something else. And the SSD pair is smaller than the NVMe pair.
Is it possible to resize the images so that they’ll fit onto the correct disks, or do I have to start from scratch?
I’m sure there’s probably some sort of mdadm invocation to shrink an existing RAID1 mirror pair, but in the absence of that, one option is to create the mirror pair you want on your 2.5" SSDs, and then shrink-and-clone the filesystem from the NVMe mirror to the 2.5" SSDs, using something like Gparted.
In that way, you end up with the mdadm pair that you wanted, and the filesystem is correctly sized. You can even clone the UUIDs for the filesystem so fstab entries won’t have to be changed.