Howto resize a Dynamical VirtualBox Disk with a Linux-Guest

By SolarEclipse | SolarEclipse | 29 Mar 2020

If you want to resize a VirtualBox Disk on a Windows-Host with a Linux-Guest (with LVM-Disks) follow the following steps:

Check the type of your Disk, it must be dynamically allocated storage

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Actual size of the Disk = 117.56GB

Insert a SystemRescueCd Live Image into the CDROM of your Linux-Guest-VM
Boot up your VM
Detect all available partitions and LVM-Volumes
- fdisk -l

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Empty space by overwriting with zeros with the tool zerofree in every detected partition and LVM-Volume.
- zerofree -v /dev/mapper/ubuntu--vg-root

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Shutdown your VM and open your cmd.exe on your Windows-Host. Change to the directory of your VirtualBox installation folder.
- VBoxManage.exe modifyhd --compact "C:\Path\to\your\vdi-file.vdi"
Done

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New size of the Disk 34.76GB