To get the disk space details of the server, simply go to command prompt and paste the below script it will give you disk space details.

powershell -command "& {Get-WmiObject -Class Win32_LogicalDisk -Filter 'DriveType = 3' |select PSComputerName, Caption,@{N='Capacity_GB'; E={[math]::Round(($_.Size / 1GB), 2)}},@{N='FreeSpace_GB'; E={[math]::Round(($_.FreeSpace / 1GB), 2)}},@{N='PercentUsed'; E={[math]::Round(((($_.Size - $_.FreeSpace) / $_.Size) * 100), 2) }},@{N='PercentFree'; E={[math]::Round((($_.FreeSpace / $_.Size) * 100), 2) }}}"

Sample Output
Caption : C:
Capacity_GB : 283.44
FreeSpace_GB : 51.48
PercentUsed : 81.84
PercentFree : 18.16