Adding disk space to any server in your Data Center can be done easily. Before you start, you should check how many resources you have left in your Data Center. You can check this in the Resources segment of your Data Center:
If you don't have enough disk space available in your Data Center, you can buy more by following this tutorial.
Adding disk space can be done by selecting the server you wish from the list by clicking on it's hostname:
After this, on the left select Storage -> Disks:
Here, click on the Edit button of the disk you wish to change.
Warning: Before adding disk space it is recommended to take a backup of your server. The process of adding disk space will cause downtime of 10 to 30 minutes.
You will be shown a slider and on the right, you'll have an input field where you can type in how much disk space you wish to have.
After you click on Save Changes, a pop-up window will appear asking you to confirm you wish to take this action:
Until this process is done, the disk will be in a locked state, and the server will show pending status.
When this process is done, the server will again be in "On" status: