This morning, I found that a virtual server had filled up it’s data drive. In order to grow the disk, I had to shut down the virtual server, then ssh to the service console and use  vmkfstools -X , where newsize is the new size of the disk, specified like “20G”.
I then started the guest, logged-in, and used diskpart extend the basic volume to use the (new) unused space on the virtual disk.
Diskpart KB
and man vmkfstools