Show size of the server

<?php
    $bytes = disk_free_space(".");
    $si_prefix = array( 'B', 'KB', 'MB', 'GB', 'TB', 'EB', 'ZB', 'YB' );
    $base = 1024;
    $class = min((int)log($bytes , $base) , count($si_prefix) - 1);
    echo sprintf('%1.2f' , $bytes / pow($base,$class)) . ' ' . $si_prefix[$class] . '';
?>