I only started with PHP a bit ago, I don't know much, but I had an idea and just wanted to see if it would work

<?php

// Mirror server
$mirror = 'http://www.mirrorserver.com/';

// Files directory
$dir = 'x71';

// Where to get the current server load
$getLoad = '/proc/loadavg';

//Where to get the mirror server's load
$getLoad2 = 'load.php';

// Gets the name of the file requested
$file = $_GET['file'];

// Checks to make sure the request is valid, and stops executing code if it isn't
if ( strstr($file, '/') || empty($file) || !strstr($file, '.') )
exit;

// Gets the server load for the current server
$handle = fopen($getLoad, 'r');
$load = fread($handle, '5');

// Gets the server load for the mirror server
$handle = fopen($mirror. $getLoad2, 'r');
$load2 =fread($handle, '5');

// Checks to see if the mirror server has a lower load and redirects if it does
if ($load > $load2)
header('location: ' . $mirror . '?file=' . $file);

// Gets the proper location of the file
$newfile = '/filesystem/path/to/file/' . $dir . '/' . $file;

// Checks to see if the file exists, and redirects if it does
if ( file_exists($newfile) )
header('location: /' . $dir . '/' . $file);
else
echo 'Error.';

?>

Can anyone tell me if there's a problem, what it is, and how it can be fixed. Also, is it secure?

IT will take less time to let the page load, whatever the load, than doing remote fopen and checking the load. Does the servers allow remote fopens?

Just FYI it's good practice to die() or exit() after sending redirect headers.

i think it is ok, i like to use {} , anyway it all on your own favorite

Neat idea. I haven't tested your code, but it looks functional.

Gave me an idea for writing a php based load balancing system :)

Have you considered doing something like weighted random numbers to pick the server?


$randomNumber = mt_rand(0,100);
if($randomNumber <= 40) {
$server = 1;
} else if($randomNumber <= 100) {
$server = 2;
}
Weight it based on the specs/traffic of the servers. If only two servers are involved there's no need for the second if. I've never tried anything like this, but it should work fine.