I couldn't boot this morning over a kernel modules thing, which is sorted now. It gave me grief because my high mileage Live USB chose that moment to die. So I decided to put a second system on a backup platter disk I have in that box on SATA.

So I have to partition it, which means repartitioning & copying back the
nearly 1Gig of data, unless there's a clever way out? The disk is formatted ext4 in one partition.

If I think what you are saying is that the data is on the computer disk, which can be accessed, but not booted, just create a link to what you want, from the one that can be booted....

Yes, but no.

For one thing, I can't specify an EFI parttion, or a / partition. For a second, there's no bootloader.

I may get by with the EFI, but not the other. Normal boot is on nvme, as is win11 mainly because I saved money by paying for win10, and they upgraded that without my consent. I appear there periodically for updates. So it's press F11, and you get a choice of bootable partitions. I don't think symlinks will do there.

It's either that or go through the messing of replacing elilo with grub or rEFInd, neither of which I fancy. elilo is automagic, sweet, & simple, 99% of the time.

Very little of the above makes any sense to me, but as to this ...gparted.

If indeed the filesystem is on the raw device rather than a partition as stated there is no simple way to do it. Think of it as an opportunity to create the backup you should have anyway.

It's OK. I thought there might be a clever way out with doing something to one end of the disk, but I've started on the copying. It's from a usb disk but I have the day. The trick was to avoid putting myself under pressure to do it yesterday. I'm linear like that.

And the subject is wrong. It's actually 1TB of copying, not 1G. But I imagine you guessed that.