Are the servers in your datacenter energy-efficient? Well, that rather depends on what your definition of "server" is.
Bill Clintonesque as that may sound, it reflects one of the many conundrums the EPA faces as it attempts to hammer out Energy Star specifications for server hardware. The department has issued the first draft of the spec [PDF], and it's seeking input from interested stakeholders by March 14.
Interest in the topic should certainly be keen among server vendors as well as chipmakers: Given the growing trend among companies to be greener, an Energy Star stamp could prove a significant selling point for servers down the road.
The draft document reflects one of the biggest challenges the EPA faces in devising an Energy Star specification for servers: They're far more difficult to meaningfully categorize in the context of energy efficiency than end-user hardware such as PCs and laptops.
"EPA would like this specification to be as inclusive as possible but also understands that some of the more complex or niche server types and applications may not be easily addressed under this specification," the Energy Star Draft 1 document reads. "Several stakeholders have suggested that the specification focus on 'volume' servers. However, the term 'volume' is used to classify server types based more on price than function. For purposes of this specification, a computer server definition should be specific enough to clearly delineate based on intended application, hardware/software, and/or operational requirements."
That said, the draft spec proposes the following definitions:
Small Floor Standing or Rack Mounted:
- 2 to 4 Processor Sockets, up to 16 processor cores
- 2 to 16 DIMMs
- 1 to 6 internal disks
- 2-4 integrated network adaptors
- 4-8 option slots for adapters to expansion units or networks
- 1 to 5U of rack space
Medium Floor Standing or Rack Mounted:
- <16 processor sockets
- < 64 processor cores
- < 64 DIMMs
- < 16 internal disks
- 2-8 integrated network adapters
- 10-30 option slots for adapters
- Typically can address upwards of 2,000 disks in expansion units
Floor-Standing and Multiplex Large Scale Servers:
- < 128 processor sockets
- < 1024 processor cores
- < 1024 DIMMs
- > 16 internal disks
- 2-8 integrated network adapters
- More than 20 option slots for adapters
- Can address upwards of > 2,000 disks
- Ability to chain many systems together to present a single system environment (multiplex)
The spec also proposes defining a blade server as "a computer consisting of, at minimum, a processor, memory and hard drive that relies on certain shared resources, contained in a blade chassis, such as power supply(s), cooling, networking, system management, and storage. Blade servers are incapable of operating independent of the blade chassis."
One question the EPA seeks to answer pertains to maximum idle power requirements: How much power should an Energy-Star compliant server be permitted to consume while in idle?
"[It] is EPA's understanding that servers typically spend a significant amount of time in an idle condition. The idle state may occur at any time of the day ... when servers are consuming what could be considered high amounts of power while waiting for client requests," the draft states. "EPA believes that to the extent that the idle state for servers will persist due to numerous factors in terms of how datacenter workloads are managed, there exists the opportunity within this specification to recognize those servers that idle at lower power consumption levels. EPA is interested in receiving stakeholder feedback on the inclusion of this requirement as well as the potential use of the SPECPower test procedure and output for purposes of evaluating idle performance."
Another big question: What should the power supply efficiency requirements be? The EPA will be more specific on this key point in the second draft. For now, it says that "efficiency will be measured at several loading points. Since many of these power supplies are used in redundant configurations, EPA felt it was important to include lower loading points, such as 10% and 20% of rated output. Similarly, EPA is interested in addressing power factor at these loads in addition to the 100% load. While a power factor of 0.9 is reasonable at 100% load this level may prove more challenging at lower loading points."
Other criteria spelled out in the draft Energy Star spec for servers: "All servers must have the ability to provide real time data on AC power consumption, inlet air temperature, and processor utilization during server operation," and "qualified computer servers must come equipped with hardware power management and virtualization capabilities."
More information about the EPA's Energy Star initiative for server is available at the Energy Star Web site.