Ubuntu 14.01 LTS 16GB RAM Power Edge Dell Dual Xeon 1.9 (8 cores total)
about 1/week I experience a horrendous slowdown on websites.
mail seems to run fine, I've installed a ton of diagnostic tools to see the problem but i can't fix it, htop shows all cores pegged, websites take like 10 seconds to first byte or error 500 out all together on complex .php sites.
the box has 17 sites.
Attatched are some htop results
Any thoughts or direction on how I can fix this? I'd like to put another important site on here but im scared because of these slowdowns.