For one of my courses, a virtual machine was provided in VMDK format and after having some trouble running it locally, I wanted to convert it to a standard LVM image so I could run it on my cloud.
The OVA image can be converted to VMDK by simply unpacking it with tar. The VMDK then needs to be converted to RAW (you might need to install VirtualBox but you don't need VMWare):
VBoxManage clonehd --format raw image.vmdk image.raw
You can then see which partitions you have by running fdisk -l on it.
Choose an unused loopback device to present the RAW file on:
losetup /dev/loop10 disk.raw
Then run kpartx to find the partitions on the loopback device:
kpartx -va /dev/loop10
And then mount whichever partitions you want from the loopback interface to a folder:
mount /dev/mapper/loop10p1 temp