Click the History Graphs button for your instance to load it's history page. From here you can check your instance's system usage. By default Cortex shows the past hour of usage. You can change this to show the past hour, two hours, six hours, day, two days, or the past week by selecting the approprite time in the top-right hand corner of the graphs window and clicking the refresh button.

Your instance's Bandwidth History graph shows two lines for inbound and outbound network usage. The darker line represents traffic outbound to the Internet, while the lighter shows your instance's inbound network traffic. Below the graph is a calculation of your server's total and average inbound and outbound traffic for the duration of the graph. Network traffic is measured in kilobit or megabit (not bytes).

CPU and memory use are measured on individual graphs on your instance's history page. CPU use, as shown on the Instances page, is measured as a percentage of the total CPU usage on your system. If your instance is using 25% CPU power on a four processor system, then it is using 100% of one processor. Memory is measured in megabytes on the memory history graph