A memo about how to increase disk/SSD/HDD capacity for Ubuntu in VirtualBox.
There’s something called Global Tools on the top screen, from which you can increase HDD capacity.
おやぢチップス (91)：VirtualBox 容量拡張が簡単にできるようになりました - 北の窓から（芦田っち）
There’s still more to do - continue from “2 HDD partition operations in Ubuntu” on the following page.
VirtualBox環境でのUbuntuのHDD容量変更方法 - Qiita
I think you should take a clone before doing this.