It might be helpful to know:
Type of disk in Proxmox, eg qcow2 or raw?
Type of OS used, NS8 supports Rocky, Debian, Alma and others.
Type of filesystem used by host OS (ext4, xfs, btrfs)?
A generic solution in Proxmox would be to fire up your NS8 using an ISO Image of SystemRescue
(previously called SystemRescueCD).
Boot using generic settings in SystemRescue, this works well in Proxmox (I am a confirmed Proxmox buff in this forum), and start the GUI with startx when it’s booted.
In the GUI, start gparted under System and check disks, partitions and expected sizes. GParted can fix and enlarge all listed filesystems and also repair them if needed.
Don’t forget to make a backup first in Proxmox, if using PBS it’s really fast, but even without, it’s always worth it!
My honest suggestion?
Spin up your own, following the instruction below.
Forget the pre-built images. It’s well worth the time, depending on hardware about 20 minutes…
Good Luck
My 2 cents
Andy
These may help too: