HP is stripping down to scale out. Today the company is launching a line of servers and services targeting the cloud computing market, which is accounting for a growing chunk of server sales. HP's Extreme Scale-Out (ExSO) portfolio is designed to appeal to cloud-builders' focus on energy efficiency and cost, and be delivered by the rackload.

HP's ambitions are built around the ProLiant SL server line, which features a "skinless" architecture with a lightweight rail and tray design. The new servers are deployed in HP's new ProLiant z6000 chassis, a 2U frame housing shared power supply and fans. The common chassis allows customers to choose between three ProLiant SL configurations optimized for maximum memory, storage or processing power.

On each server, HP is mounting the disks on the side rather than the front, allowing better air flow through to the fans on the rear of the chassis. The i/o cabling is on the front of the server, allowing it to be serviced from the cold aisle.

"We've designed it for power efficiency and good airflow," said Ed Turkel, manager of business development for HP Scalable Computing & Infrastructure. "In this environment they typically don't need a lot of management features. We think of this as a lean and mean environment."

“Customers with scale out business models need solutions that make every dollar, watt and square foot in the data center count,” said Christine Reischl, senior vice president and general manager of Industry Standard Servers, HP. “These customers are pioneering ‘extreme’ businesses and their extraordinary requirements are pushing beyond traditional architectures."

HP is hardly alone chasing the cloud computing market, and enters a niche where rivals IBM (iDataPlex), Dell (CloudServer) and Rackable (MicroSlice/CloudRack) have already introduced servers tailored for customers with scale-out data centers.

HP is touting the ProLiant SL's ability to put data centers on a diet, both in terms of energy consumption and the actual weight of the racks. The SL line with Intel Xeon 5520 processors uses 28 percent less power than the HP ProLiant DL160 Server, and its skinless design makes it lighter. HP says the new SL2x170z is about half the weight of traditional rackmount servers, offering savings on shipping costs and allowing lower floor support requirements.

Here's a comparison of the models and features:

HP ProLiant SL160z: This server is optimized for workloads with large memory requirements, with 18 DDR3 DIMM sockets (compared to 16 for the other SL models). The SL160z also has two PCI slots to support large memory-cache apps.

HP ProLiant SL170z: Storage capacity is the focus of this configuration, which offers 6 large-form Serial ATA or serial-attached SCSI drives to support storage-intensive workloads like web search and database applciations.

HP ProLiant SL2x170z: With two servers in each 1U tray, this model is designed with extra compute power for high-density HPC environments and web front-end applications.

HP says the ExSO portfolio is ideal as the inner workings of the HP POD data center container. "We're talking to some customers about deploying by the POD," said Turkel. "There's a lot of interest in that. But we expect most customers will want to deploy these servers in a traditional data center."

HP is also introducing "Extreme Operational Support" for ExSO customers, which it says provides installation services specifically designed for data centers with thousands of servers. ExSO customers can also opt for an on-site "seed inventory" of replacement parts to speed repairs.

While much of the scale-out focus is on cloud computing, HP's new product line was welcomed by the company's partners targeting high-performance computing (HPC), including Microsoft.

“HP’s new Extreme Scale-out portfolio directly addresses a number of key challenges faced in today’s mega-data centers, such as efficiency in power and cooling, while maximizing performance and density per square foot," said Vince Mendillo, director of HPC marketing for Microsoft.