Error in the space of the disk

[Ardust]

I'm new in virtualbox so excuse me for my lack of knowledge.
I have an Ubuntu OS in a virtual machine with a 100GB dynamic VDI disk.
It was working great but yesterday Ubuntu notified me that I had 80 MB of free space
in the disk and then stopped working. I turned off the vitual machine and then tried to restart
it but It was not woking. I checked the disk and VMBox said it was full, so i decided to
copy it on a new disk with 150GB. My surprise was when the copying process finished
and the new disk had only 25 GB occupied, not the 100 GB.
¿Anyone knows why?

[scottgus1]

I'm not sure what went awry in the copy-to-a-new-disk process, but there are ways to expand the original disk. This assumes you were not using snapshots.

If the original disk was dynamically expanding, see How to Resize a Drive.

If the original disk was fixed size, make a clone of it using Mpack's CloneVDI, and "Keep Old UUID" and increase the size. If you make the clone same name as the original and in the original disk's folder, the clone will replace the original in the VM, and the original will be renamed. You might need to do step 2 of the Resize a Drive tutorial.

[Ardust]

I tried to reseize it but did not work, how do i now i am using snapshots?

[scottgus1]

how do i now i am using snapshots?

I now notice that none of your disks in the screenshot show the "child disk" side arrow icons. It appears you're not using snapshots, good.

I tried to reseize it but did not work,

There was a lot of suggested info that you completed rather quickly, in only 6 minutes in fact. What exactly did you try?