Convert VirtualBox dynamic VDI disk image to static, fixed VDI

Question

I've originally created my VDI to auto-expand to 20GB of virtual capacity.

For performance reasons, I would like to convert them to linear, that is, to have a single, non-sparse, 20GB file sitting on the disk, instead of the dynamically expanding, prone to fragmentation image.

Answer 1

Use vboxmanage clonehd:

vboxmanage clonehd olddisk.vdi newdisk.vdi --variant fixed