VirtualBox useful tips
Change UUID
Got error like this
Cannot register the hard disk ... because a hard disk ... with UUID ... already exists.
Run this
cd "C:\Program Files (x86)\Sun xVM VirtualBox"
VBoxManage internalcommands sethduuid "C:VirtualBox VMs/MY VM/MY DISK.vdi"
Change dynamic disk size
cd "C:\Program Files (x86)\Sun xVM VirtualBox"
VBoxManage modifyhd "C:VirtualBox VMs/MY VM/MY DISK.vdi" --resize 16384
# Then maybe you have to use the GParted software to configure the disk
Run zerofree to reduce the disk size
Log into the Linux VM to delete all unnecessary files/folders
Install the zerofree on this Linux VM. Example for Ubuntu
sudo apt-get install zerofree
# Check the free disk
df -hl
Re-start the Linux VM and boot into recovery mode
Press ESC while the VM is starting then choose "Advanced options for Ubuntu", then "recovery mode", choose "root"
zerofree -v /dev/THE_SDA_OR_SDB_NAME
After above command finished, run this command on Windows
cd "C:\Program Files (x86)\Sun xVM VirtualBox"
VBoxManage modifyhd --compact "C:VirtualBox VMs/MY VM/MY DISK.vdi"