<?php
//On windows:
$hdwinC = disk_free_space("C:");
$hdwinD = disk_free_space("D:");
echo "Diskspace left on C: $hdwinC<br>";
echo "Diskspace left on D: $hdwinD";
//Linux:
$hdGnu = disk_free_space("/");
echo "Diskspace left on / $hdGnu";
?>
disk_total_space