Progress state: VBOX_E_NOT_SUPPORTED

deathstar> VBoxManage showhdinfo XP.vdi 
UUID:           fa2d24af-bd52-4928-89d3-c8c5feeb7b75
Parent UUID:    base
State:          created
Type:           normal (base)
Location:       /root/VirtualBox VMs/XP/XP.vdi
Storage format: VDI
Format variant: dynamic default
Capacity:       60000 MBytes
Size on disk:   4276 MBytes
In use by VMs:  XP (UUID: 357d04a7-6758-4c56-b063-63909ce85fb3)


deathstar> VBoxManage modifyhd XP.vdi --resize 6144
0%...
Progress state: VBOX_E_NOT_SUPPORTED
VBoxManage: error: Resize hard disk operation for this format is not implemented yet!

I have a working XP.vdi around 4GB in size, ruing on a Linux Host: 3.16.0-4-amd64 #1 SMP with no vtx.

I first 'released' the image, then did a resize to 5GB and it worked, unfortunately I was having trouble with gparted so I didn't use gparted on the ntfs.

I got gparted through kvms working, then came back to this image but gparted wasn't showing me any extra space on the disk (the unallocated is my linux drive).

Windows also shows i'm using 4.6GB/5GB

but VirtualBox only sees 4.18GB :

Bottom line is, I think i'm only using the original 4.16GB of space in-spite of what Windows/Gparted think. I tried a further larger resize to 6GB using VBoxManage but that failed with the error above.

What do I do?