磁盘配置：

'disks' => [

        'local' => [
            'driver' => 'local',
            'root' => storage_path('app'),
        ],
        'c-drive' => [
            'driver' => 'local',
            'root' => 'C:\\',
        ],
        ....

$old = Storage::disk('c-drive')->files($dir);