Script to delete lot's of files without a big impact on the system IO

deleteFiles.php

<?php
// path where the files should be deleted
define('PATH', '/.');
// delete only files older than OLDER_THAN_DAYS days
define('OLDER_THAN_DAYS', 14);
// delete only files that match MATCH_NAME
define('MATCH_NAME', '/some regexp/i');
// do NOT actually delete the files
define('DRYRUN', false);
// sleep SLEEP_USEC microsecconds after each delete
define('SLEEP_USEC', 5000); // I have good experience with setting it to 5 milisecs

$older_than = time() - OLDER_THAN_DAYS * 24 * 60 * 60;
$to_delete = array();
$success = 0;
$failed = 0;
$count = 0;
$echo = "";
$freespace = 0;

try {
	$dir = new DirectoryIterator(PATH);

	foreach ($dir as $file) {
        if (!$file->isDot() && $file->isFile() && $file->getMTime() > $older_than 
            && preg_match(MATCH_NAME, $file->getBasename())) {
			if (DRYRUN) {
				$success++;
				$freespace += $file->getSize();
			} else {
				$size = $file->getSize();
				if (@unlink ($file->getPathname())) {
					$success++;
					$freespace += $size;
				} else {
					$failed++;
				}
				usleep(SLEEP_USEC);
			}
			$count++;
			echo "\033[".(strlen($echo))."D";
			$echo = "Went through " . $count . " files and deleted $success successfully and $failed unsuccessfully. Made " . round($freespace / 1024 / 1024) . "M of freespace.";
			echo $echo;
		}
	}
} catch (UnexpectedValueException $e) {
	throw new Exception("Directory path wrong [".$e->message."]");
}