Sentilla, which makes software to control and analyze equipment in your data center for optimum efficiency, has raised $15 million in a third round of funding.

SingTel Innov8, the VC arm of Singapore telco carrier, joined existing investors and now owns 23.4 percent of the company.

Sentilla has created software that effectively monitors and manages power consumption and other metrics in data center equipment like air conditioners, servers and storage devices. But as time goes on, Sentilla has begun to graduate from analyzing data centers for energy efficiency to analyzing them for overall computing efficiency and effectiveness.

Has a data center taken full advantage of virtualization? Are there servers or storage units that are consuming power but not churning out necessary calculations? Can applications be rolled to different server banks or data centers to better economize on overall hardware and infrastructure?

"We reduce infrastructure sprawl," said CEO Mike Kaul in an interview. "We're focused on the totality of getting data centers to provide the most output for the least input."

Last year, the company estimated that the top 40 online retailers spend an estimated $110 million more on energy than they should in preparing for Cyber Monday, the first workday after Thanksgiving that's been enshrined as the start of the online holiday shopping season. The excess power comes from servers churning in idle and untracked assets waiting around for the big shopping bump.

"The carbon impact of this power waste is approximately 727 million pounds of carbon dioxide. That's more CO2 than emitted by all of the round trip flights each year between SFO and JFK,"  Joe Polastre, Sentilla's CTO and co-founder told us back then.

As we've said before, green IT remains one of the more promising markets in the renewable world. (Read the full opus with vendor guide here.) Internet companies are facing escalating power bills; utilities are willing to give refunds and credits to people willing to retrofit their data centers; and IT companies like Intel, Hewlett-Packard and IBM have been aggressively touting technologies that can help reduce those bills. On top of that, the benefits of these technologies can be quantified.

SingTel Innov8 probably has additional motives on top of that. Approximately 51 percent of Singapore's power gets consumed by air conditioners, fans, and refrigeration. Let me repeat: 51 percent. That's what happens when you build a modern economy smack on the equator. To lower power bills, the country has to tackle the data center problem. Some large customers have also begun to trial energy efficiency devices in data centers before rolling them out to the building at large.

Some green IT ideas -- like running your data center on DC power, replacing hard drives with flash memory, building modular or low-energy data centers, or swapping old lights for LEDs -- can come with a bit of a price tag. Others, like the services Sentilla offers, are less expensive and revolve around software that can run on top of existing infrastructure. Sentilla charges a per-rack licensing fee.

The data center management market isn't swamped with competitors like solar, but large companies do have their choice of vendors. SynapSense, a competitor, raised $16 million in a round in July. Other names to watch include Vigilent and Power Assure. At an NTT data center, Vigilent shut off 9 of the 14 existing AC units and the temperature went down.

While some of these software/management companies could remain independent entities, a good number will get gobbled up by the IBMs and Oracles of the world. (HP, in fact, tried to conquer this market a few years ago with homegrown technology that ended up needing some tweaks.) Since the IT giants understand this industry and have a built-in customer base, acquisitions in this segment are probably more likely at this point than, let's say, IBM buying a home networking company.

Cisco might become more of a player here, too. In 2010, it bought a mesh company called Arch Rock, ostensibly to help it in the smart grid push. Most of Arch Rock's work to date, however, had been in data centers. Considering how Cisco's grid and building management plans have gone, going back to its roots with Arch Rock may not be a bad idea.

Tags: arch rock, cisco, data centers, facebook, google, green it, hewlett packard, power assure, powerassure, sentilla, servers, storage, synapsense, vigilent