Mirror就是我们所说的镜像，主要目的是为了防止一个地点被(deleters or site op)删除后仍然有地方下载。
Mirror - An exact copy of a web site that is stored on a different server. Using multiple locations
for warez sites allows the site to be accessed using a different address if the main site is deleted.
镜像-置放在不同伺服器上同样内容的东西，