Cooling is a familiar problem to most facility executives who deal with data centers. Whether it's dealing with a hot spot caused by a server or simply keeping a data center running at a temperature that will keep servers operating reliably, cooling has emerged as a major trouble spot.

I recently toured a data center meant to serve as a test lab, and as such, it employs a variety of technology. The data center's server rooms are home to both traditional computer room air conditioning (CRAC) units and in-row cooling. A sophisticated series of submeters allowed researchers to compare the energy use with differing cooling configurations.

One interesting comment I heard from one of the data center operators is that in-row cooling is more efficient because in-row cooling doesn't have to push the air as far as CRAC units, saving on fan energy. The readouts on the submeters on the wall bore that comment out.

Perhaps that's one reason why research firm Gartner is predicting that in-row and in-rack cooling will become more common.