Hub

A hub is a basically a service used to logically group and monitor it's associated devices. Generally you will have one hub per machine. However it's possible to utilize multiple hubs depending on the workload you have. For example, if you have many devices to monitor, a single disk might not be able to handle the load and it may be necessary to split the load across multiple hubs. Since you can set a separate "Storage Root" for each hub, this allows you to separate disk for each hub.