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We have an Amazon EC2 instance which is firing off a High CPU alert once a day. It happens at exactly the same time every single day.

In looking at the cpu utilization history I see one spike that occurs at either 6:09, 6:14, 6:19 or 6:24 each day - only 1, but over the past 2 weeks that spike has rotated through those moments.

A second spike occurs at 8:59; this second one causes the alarm and is ALWAYS at 8:59.

How can I figure out what's going on?

The server is a web server running a .net application. There are no services installed other than what comes with Windows. There are no jobs firing from other parts of the system that hit this machine.

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Is it the free tier micro instance? in this case the CPU is share between more VMs and you can get CPU performance issues. – POLLOX May 20 '14 at 9:19
up vote 2 down vote accepted

Use perfmon (Windows Performance Monitor) to log All Instances of the counter Process\% Processor Time. Set it to log during the time frames you are experiencing alerts, and then review the data to determine the process spiking during those timeframes.

Possible dupe of:

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Another important parameters in the CPU performance are: Processor\% Interrupt Time System\Processor Queue Length – POLLOX May 20 '14 at 9:17
I'm accepting this as it will likely lead to an explanation for someone else. However, I wanted to verify the server this alarm corresponded to. After going through all of our instances (4) none of them are associated with this alarm. An older instance that we had terminated used to be tied to it so I'm guessing it's just bad data. – NotMe May 20 '14 at 13:57

Try Sysyinternal Process Monitor to inspect real time activity.

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