A lot of smart people are getting excited for this week's launch of SignalFx, a cloud company founded by a Facebook engineer and a virtualization veteran who helped architect VMware's IPO.

SignalFx's announcement came at the end of a two-year quiet period, as it revealed it has raised $28.5 million in funding across two super-secret rounds led by Andreessen Horowitz — in fact, Ben Horowitz joined the board — and Charles River Ventures, respectively.

"These are some of the smartest and best people we've ever had the privilege of working with," Horowitz's partner Marc Andreessen tweeted this week.

The company was in stealth mode for two years because it wanted to make sure it got the technology right. Yelp was among the customers who helped SignalFx beta test its offerings.

The reason everybody's so jazzed about SignalFx: Cloud applications — stuff like databases and servers hosted in large data centers elsewhere — are getting big and complicated, with lots of moving parts. They're getting so big and so complex, in fact, that it's hard to keep tabs on them and make sure they're running.

During his time on Facebook's infrastructure team, co-founder Phillip Liu had to figure out how to solve this problem for the social network as it grew from tens of thousands of servers to hundreds of thousands. Those are scales that server monitoring tools from companies like Microsoft and Oracle just weren't originally built to address.

Not everybody has those kinds of growth problems. But as more people turn to the cloud, they're going to run into the same roadblocks.

"People are all going through the same kind of transition," Liu says.

The solution, developed in conjunction with VMware and Delphix veteran and co-founder Karthik Rau, takes those lessons and packages them up in something that's easy for developers who are building applications in the cloud to use to make sure their apps are happy and healthy.

The secret sauce is SignalFlow, an analytics tool that offers up-to-the-minute, detailed reports on stuff like how long it's taking for customers in Malaysia to access your website from their tablets (for example).

For the average IT guy, Rau says, SignalFx helps them change their thinking about how apps are built and managed. Before, Microsoft may have sold them something to help manage the e-mail server sitting in the closet. Now, the e-mail service comes from the Office 365 cloud, where all of the servers are managed by Microsoft itself.

"You now have the people who built the software managing the software themselves," Rau says.