From time to time, my website will be down and giving "refuse to connect" error. When I check the resource usage, I see graphs like this one, which shows constant CPU usage spike on a single day(12/19).
I think these must be the reasons my site is up and down. Now my site is a rather small sites with daily pageview of no more than 3k. So the normal visiting shouldn't be causing this usage spikes. I suspect there must be some misconfiguration( which is unlikely because I just use Godaddy's default cPanel) or some degree of breach. My questions are:
- In general, what causes high CPU usage and high memory usage?
- For each of high CPU usage and high memory usage, will they cause the website to be down or just slow?
- I have SSH access, how do I track the reasons for these usage spikes?
Thanks very much for your help!