How to shrink accidentally expanded VDI?

Question

I've accidentally expanded a dynamically allocated VDI image to ~150TB instead of ~150GB using VBoxManage modifyhd (a lesson to learn: [--resize <megabytes>|--resizebyte <bytes>])

Now, when I'm booting the virtual machine, I get the following warning:

The medium '/home/bbalint/VirtualBox VMs/wii/wii.vdi' has a logical size of 143TB but the file system the medium is located on can only handle files up to 7TB in theory.

To fix my mistake, I tried to resize the VDI again, but now I get the following error:

$ VBoxManage modifyhd {d013c1f5-3f1f-4918-a079-ee27f4b398a3} --resize 150000
0%...
Progress state: VBOX_E_NOT_SUPPORTED
VBoxManage: error: Resize hard disk operation for this format is not implemented yet!

This is strange, since I did not change any other parameters of the image besides the size:

$ VBoxManage showhdinfo {d013c1f5-3f1f-4918-a079-ee27f4b398a3}
UUID:           d013c1f5-3f1f-4918-a079-ee27f4b398a3
Parent UUID:    base
State:          locked write
Type:           normal (base)
Location:       /home/[...]/VirtualBox VMs/wii/wii.vdi
Storage format: VDI
Format variant: dynamic default
Capacity:       150000000 MBytes
Size on disk:   64526 MBytes
In use by VMs:  wii (UUID: 5810c0ba-4776-48d7-807f-1116295688a0)

How can I fix this?

Answer 1

I have done the same mistake :(

This is not a direct solution but at least I have been able to recover my data using a method I found here.

Essentially you use nbd and qemu to create a /dev/nbdx device

sudo modprobe nbd max_part=16
sudo qemu-nbd -c /dev/nbd0 bad.vdi

Then I created a new VDI with the correct size:

VBoxManage createhd --filename new.vdi --size 15000 --format VDI

I then used the same nbd and qemu method on it: sudo qemu-nbd -c /dev/nbd1 new.vdi, and then cloned the partition (I used gparted: sudo gparted /dev/nbd0 /dev/nbd1).