Why doesn't ubuntu server see all memory?

Question

virtual box

The VDI memory in the virtual machine (Virtualbox) has run out, I increased it by 10-15GB, so I start the server and for some reason it does not see these additional gigabytes. Please help me sort it out.

Answer 1

So memory or disk space?
If the disk is still necessary to push the file system.

Answer 2

If LVM was not used, then you need to boot from some live-cd thread and increase the size of the partition on the disk. And then you increased the disk, but the partition itself will not increase.
After you increase the partition, in Linux the file system on it will need to be corrected like
sudo resize2fs /dev/sda1