There are many blog posts, articles, and even books written on how to effectively interview software engineers. Hiring systems administrators is a bit more prickly of a topic, for a few reasons.
- You generally hire fewer of them than you do developers.
- A systems administrator likely has root in production. Mistakes will show more readily, and in many environments “peer review” is an aspiration rather than the current state of things.
- It’s extremely easy to let your systems administration team become “the department of no.” This can have an echo effect that pumps toxicity into your organization. It’s important to hire someone who isn’t going to add overwhelming negativity.
Every job interview since the beginning of time is built around asking candidates three questions. They’ll take different forms, and you’ll dress them up differently each time, but they can be distilled down as follows.
- Can you do the job?
- Will you like doing the job?
- Can we stand working with you?
Doing the Job
This is where the barrage of technical questions comes in. Be careful when selecting what technical areas you want to cover, and how you cover them. Going into stupendous depth on SAN management when you don’t have centralized storage at all is something of a waste of time.
Additionally, many shops equate trivia with mastery of a subject. “Which format specifier to date(1) will spit out the seconds since the Unix epoch began?” The correct answer is of course “man date” unless they, for some reason, have %s memorized– but what does a right answer really tell you past a single bit of data? Being able to successfully memorize trivia doesn’t really speak to someone’s ability to successfully perform in an operational role.
Instead, it probably makes more sense for you to ask open ended questions about things you care about. “So, we have a lot of web servers here. What’s your experience with managing them? What other technology have you worked with in conjunction with serving data over http/https?” This gleans a lot more data than asking trivia questions about configuring virtual hosts in Apache’s httpd. Be aware that some folks will try to talk around the question; politely returning to specific scenarios can help refocus them.
Liking the Job
Hiring people, training them, and the rest of the onboarding process are expensive. Having to replace someone who left due to poor fit, a skills mismatch, or other reasons two months into the job is awful. It’s important to suss out whether or not the candidate is likely to enjoy their work. That said, it’s sometimes difficult to ascertain whether or not the candidate is just telling you what you want to hear. To that end, ask the candidate for specific stories regarding their current and past work. “Tell me about a time you had to deal with a difficult situation.” Push for specific details– you don’t want to hear “the right answer,” you want to know what actually happened.
This questioning technique leads well into the third question…
Not Being a Jerk
If you think back across your career, you can probably think of a systems administrator you’ve met who could easily be named Surly McBastard. You really, really, really don’t want to hire that person. It’s very easy for the sysadmin group to gain the reputation as “the department of no” just due to their job function alone– remember, their goal is stability above all else. Your engineering group (presuming a separate and distinct team from the operations group) is trying to roll new features out. This gives way to a natural tension in most organizations. There’s no need to exacerbate this by hiring someone who’s difficult to work with.
A key indicator here is fanaticism. We all have our favorite pet technologies, but most of us are able to put personal preferences aside in favor of the prevailing consensus. A subset of technologists are unable to do this. “You use Redis? Why?! It’s a steaming pile of crap!” is a great example of what you might not want to hear. A better way for a candidate to frame this sentiment might be “Oh, you’re a Redis shop? That’s interesting– I’ve run into some challenges with it in the past. I’d be very curious to hear how you’ve overcome some challenges…”
Remember, the successful candidate is going to have to deal with other groups of people, and that’s a very challenging thing to interview for. It also helps to remember that interviewing is an inexact science, and everyone approaches it with a number of biases.
For this reason, I strongly recommend having multiple interviewers speak to each candidate, and then compare notes afterwards. It’s entirely possible that one person will pick up on a red flag that others will miss.
Ultimately, interviewing is a challenge on both sides of the table. The best way to improve is to practice– take notes on what works, what doesn’t, and adjust accordingly. Remember that every hire you make shifts your team; ideally you want that to be trending upwards with each successive hire.
 I’m partial to http://smile.amazon.com/Recruit-Hire-Great-Software-Engineers/dp/143024917X?sa-no-redirect=1 myself.
 For purposes of this article, “systems administrators” can be expanded to include operations engineers, devops unicorns, network engineers, database wizards, storage gurus, infrastructure perverts, NOC technicians, and other similar roles.
 For purposes of this article, “developers” can be expanded to include… you get the idea.