Just wondered how people generally charge for system admin time. For things like fixing small bugs, upgrading apache then I just charge for the hour and thats it. However in the following setup how would you charge?

I'm diagnosing a server that crashes randomly so I login at say 7am and logout at 11am so I was logged in for 4 hours. In that time I only did say 55 minute or work as the rest of the time top was running to see what was going on. Now I would charge for 1 hour but do people normally charge the full 4 hours or somewhere in between?

Rus