My rails installation was chugging along nicely. Last night we had to perform a hot-patch with was really a standard deploy of some exception code. Once capistrano finished the operation one of our admins discovered that there were two long running passenger processes. While we have deployed release over the past two weeks it would appear that these processes have been here and alive the whole time. Granted they could have been zombies or any other artifact and at this point we do not know what state they were in.

Which leads me to the question: There are so many moving parts between the rails application and the OS/hardware that being a SME is probably no longer possible. So; how does a sysadmin perform root-cause analysis with any certainty?

And: When do I just start rebooting servers?