I have a 1TB SATA hard disk from my old desktop, and the entire thing is an ext4 /home partition (/, /boot, and swap were all on another hdd). It is now in a USB2 enclosure and I want to use it to back up my current laptop /home.
To do this I need to shrink the /home partition on the 1TB backup drive. It only uses about 500GB so that shouldn't be a problem, I'll start the laptop with an Ubuntu live USB, plug in the 1TB drive, and use Gparted to shrink the 1TB /home partition to ~500GB.
Then I can create a second partition in the newly freed space, and
cp -ax my laptop's /home over to it.
Unfortuntely, Ubuntu Live USB can detect and mount the external hdd, and Gparted can see it's there, but Gparted can't read it and hence can't resize it. Disk Utility reports the drive is fine, no errors, so I'm not sure what's the problem. See linked pics, worth a thousand words.
Anyone know what the problem is here? Any pointers in the right direction much appreciated.