Issue Server has 8TB of total space but only 4TB appears on the plesk.

[milooMM]

My Ubuntu Server 18.04 has 8TB of total space but only 4TB appears on the Plesk. Can someone guide how to fix that?

 

[Bitpalast]

Could this be due to your partions? Normally, a disk has several partitions, and the "3" in the "/dev/md3" indicates just that. You probably have one partition with 4 GB and another at least two more with other sizes, maybe more. You can see what you have on the system with the "df" command on the linux shell.