The exception to the recommendation would be if the system storing your virtual hard disks has space restrictions and your hard disks tend to grow quickly (e.g. Having a dynamic 300 GB or 2 TB virtual disk won’t actually take up 300 GB or 2 TB on your hard drive and only takes up the actual disk space used on the disk.
It is to your advantage to use a large dynamic hard disk with a high maximum storage space to save you from having to go through this resizing process frequently. Recommendation: Use a large size dynamically expanding storage So if you have an IDE hard disk already, create a new IDE disk. Make sure the new disk you create is of the same type as your old disk you want to expand. The screenshot below pertains to VirtualBox 3.0. Note: Starting with version 4.0 of VirtualBox, to create new disk images, use the “Storage” page in a virtual machine’s settings dialog because disk images are now by default stored in each machine’s own folder. double the size) than the original hard disk to avoid problems. If you are expanding the hard disk capacity, choose a size significantly larger (e.g. You can use the dynamically expanding storage or a fixed size disk. Use VirtualBox to create a new hard disk (vdi) with your desired size.
Below are steps showing you how to resize and expand an existing VMDK or VDI virtual hard drive in VirtualBox for use with a guest virtual machine (VM). Often, people find their virtual machine hard disks are too small for usage needs.