Sometimes – whether it be a new job or an inherited system or a colleague who’s taken time off to conceive a baby – you just don’t know what the heck is going on. There’s an application running with an unfamiliar name, there’s no man page, and the font of knowledge that is Google can only spit out cryptic snatches of email from mail-archive.com. I’m going to offer a few techniques and tips to illustrate how I gather information about unfamiliar software, its files, ports and command line arguments. It’s starts off simple and gets a little more interesting towards the end.
For the purpose of this post, I’m going to pretend I don’t know what Mongo DB is. It’s a NoSQL database, very good at horizontal scaling. But let’s pretend. I’m selecting it as an example because it’s not too untidy, and helps me make my point.
You’re in the deep end at a new job, you’re on your own, there’s no documentation, and the monitoring shows that a host is running at high load. You’ve never come across this program before, and have no idea where to start. First thing to do, top: