在异地机房部署了一个MySQL灾备库，部署之后复制看起来是正常的，但是观察MySQL错误日志却发现复制线程每隔30秒左右都会断线重连一次。
MySQL输出的错误日志：
经过排查，最终发现是到机器到主力机房的路由有问题，添加路由后故障消失。
MySQL输出的错误日志：
170110 16:07:00 [ERROR] Error reading packet from server: Lost connection to MySQL server during query ( server_errno=2013)
170110 16:07:00 [Note] Slave I/O thread: Failed reading log event, reconnecting to retry, log 'mysql-bin.000362' at position 948341
170110 16:07:45 [ERROR] Error reading packet from server: Lost connection to MySQL server during query ( server_errno=2013)
170110 16:07:45 [Note] Slave I/O thread: Failed reading log event, reconnecting to retry, log 'mysql-bin.000362' at position 950196
这个故障只能在排查错误日志时发现，监控复制线程不容易检测到这个问题。
经过排查，最终发现是到机器到主力机房的路由有问题，添加路由后故障消失。
