If you haven’t worked on Google’s data center team in the past, you won’t have the exact expertise you’ll need when you join, so, although expertise is important when applying for Google data center jobs, what’s more important is a sharp and flexible mind.

No one built a network to support applications at Google’s scale before Google, so Googlers learn many of the skills required to operate and continue expanding that network on the job.

“There is no book that you can refer to,” Joe Kava, Google’s VP of data centers, says. “The technology we deploy was invented here, so you’re not going to get a person with that specific expertise.”

In the nine years that he’s been at Google, the company’s data center team has grown more than 10-fold, and it’s continuing to grow, although not as quickly as it has in some previous years, when he would hire more than 100 people per year. The core team today is big enough to where it doesn’t have to hire at such extreme rates, but the search for good people never stops, and it has gotten harder.

See also: How to Get a Data Center Job at Facebook

The data center industry has been growing rapidly over the last couple of years. Operators of cloud platforms at global scale, companies like Google and Facebook, as well as data center providers like Equinix and Digital Realty Trust, have been expanding their infrastructure around the world, and competition for talent is heating up.

That, combined with relatively low numbers of women and young people entering the data center profession, makes it increasingly difficult to find the right people – even for Google.

Read more: The Data Center Industry Has a Problem: Too Many Men

“I think it’s getting harder because the data center sector as a whole has been pretty hot,” Kava says.

His approach to hiring is in line with the company’s overall staffing philosophy, developed by Laszlo Bock, Google’s former senior VP of operations, who left last year to help other companies create the employee culture Google is famous for.

Here’s how Bock described the number-one element of his philosophy two year ago to The New York Times’s Thomas Friedman:

“The No. 1 thing we look for is general cognitive ability, and it’s not I.Q. It’s learning ability. It’s the ability to process on the fly. It’s the ability to pull together disparate bits of information. We assess that using structured behavioral interviews that we validate to make sure they’re predictive.”

That general cognitive ability is more important for people working in Google data center jobs today than ever. The cut-and-dry division of labor, where some people did racking and stacking, some provisioned servers and installed operating systems, some oversaw network connections, and others did service maintenance in production, has been replaced by automation.

With most operations tasks handled by software, you need especially sharp people on board to troubleshoot when systems fail or to figure out solutions in atypical scenarios, outside of the existing automation capabilities. This is equally true in IT, software, facilities operations and other areas.

“When something goes wrong and automation can’t account for it, figuring out why has become more of a specialty skill, and we need much higher quality people to do those kinds of corner cases,” Kava explains.

See also: What Cloud and AI Do and Don't Mean for Google's Data Center Strategy

If expertise is not the top priority, it certainly is one of the main considerations – Bock ranked it as the fifth most important factor. Not having gone through formal higher education doesn’t automatically disqualify you – although a college degree doesn’t hurt – but having solid grasp of the technical fundamentals is important.

People in Google data center jobs are generalists, or systems-level engineers, but they typically have at least foundational knowledge of computer science, electrical, or mechanical engineering.

“Having that solid engineering or technical foundation to build from is important,” Kava says. “You can acquire that foundation in different ways.”

Where Kava’s team does rely more on formal education when sorting through resumes is data center design. Most people on the design team are licensed engineers in regions where they work.

Skills he looks for in design and operations candidates run the gamut: from traditional data center disciplines like electrical and mechanical engineering, security, and supply-chain management to building information modeling and statistical probability analysis. If you’re looking at several design options, which one is more likely to deliver the right level of availability?

See also: Data Centers Scrambling to Fill IT Skills Gap

Advanced understanding of control systems is growing in importance, because Google’s data center network is becoming ever more complex and distributed. This is where knowledge of machine learning comes in handy. As we’ve written before, Google uses deep neural networks not only to figure out which ads to display at the top of your search results but also to improve its data center efficiency.

Skills? Check. Extraordinary cognitive ability? Check. The third big box is personality. Bock wouldn’t have what is more than likely a lucrative consulting gig was it not for Google’s famous company culture, and that begins with personality of the people the company hires.

The key traits there are being collaborative, being willing to take ownership of projects and issues, and being transparent. There’s no room for the knowledge-is-power attitude common in corporate environments, where people guard their influence by sharing as little information as possible.

Finally – and it’s a cliché but its importance cannot be overstated – be a pleasant person. “You want people that have a good sense of humor, people you’d like to be spending eight hours a day around,” Kava says.