如果我的服务器没有计量100mbps，我如何检查我的带宽现在已经饱和多少？

I'm designing a PHP application that works on several upload servers What I basically want to do, is to use a Cronjob that fetches reports from each sub-server, and gives me: 1- How much space is left on the drive and 2- How much the bandwidth for that server is saturated (e.g. if a server is running at full bandwidth, use another now)I'm designing a PHP application that works on s