Whether you’re setting up a large or small data center, power efficiency is one metric that will have a substantial impact on total operating costs. A lot amount of research has been done around the topic of how larger data centers can save as much energy as possible. While some suggestions, such as building your data center close to a hydroelectric plant, are not applicable to the size of data center most of us are managing, there are a number of power saving tips that apply to all server installations.
This week I’d like to look at a few tips for saving power regardless of the number of servers you’re running. You may not have control over every variable, such as the size of room or the effectiveness of the cooling system. In a perfect, world those would be part of the master design plan for the center you manage. I’ll bet most of us were handed a room full of servers where we spend our days keeping them operational. With that in mind, let’s take a look at a few ways we can make our data centers more power efficient.
Install Power Efficient Servers
Rack servers consume the most energy in the typical data center, and they also waste the most energy. Most servers run at or below 20% utilization, yet many still draw full power throughout the day. When purchasing servers for your company or when replacing old servers, it’s wise to look for products with variable speed fans instead of those with constant speed fans. Variable speed fans will keep a server cool during peak load times, then ramp down during off-hours. Servers that have met the Energy Star efficiency requirement are, on average, 30% more efficient than those without the designation.
Solid State Drives (SSDs) have increased power efficiency because they consume less energy than mechanical drives and they don’t create much heat, allowing the case fans to run at at slower RPM. But until SSDs are able to store multiple terabytes of data, mechanical drives will have a presence in the data center. This is certainly the case with RAID arrays where mechanical drives still dominate. I know some IT managers disable the power management features on mechanical drives, believing that throttling down servers into an idle or sleep state will cause reliability issues. While that might have been a concern years ago, today’s modern drives are designed to handle tens of thousands of on/off cycles.
Enabling power management features on your drives can impact performance, and should be weighed against potential energy savings.
One last potential energy saving tip in regards to servers is to install a power supplies per rack instead of individual server. This won’t always be possible, but it can result in energy savings. Power supplies that are even a few years old may yield a power efficiency rating of around 60% to 70%. Compare that with modern power supplies with a 95% efficiency rating and the energy savings can add up quickly. Higher efficiency power supplies also reduce cooling costs. They cost more, but are almost always worth it in the long run.
Power consumption is roughly linear to the number of storage devices in use. Planning and evaluating your storage needs will help you avoid scale up in size and energy consumption. Consolidating storage drives into a NAS or SAN are two options that allow for this when your data doesn’t need to be immediately accessible. You may be tempted to add storage to less utilized servers with drive capacity, but the added CPU resources and required cooling can drive up energy consumption when compared to installing a dedicated NAS or SAN.
Running multiple independent operating systems on a single server is one way to increase server utilization and drastically reduce your server footprint. There is some overhead added to a virtualized environment, but it’s small compared to the energy savings. But virtualization frees up rack space, reduced cooling, and helps reduce cabling and may simplify your networking needs.
Cable congestion can negatively affect air distribution throughout your data center. I know it’s not sexy, but effective cable management can help keep your servers running at optimal efficiency. Without proper ventilation and airflow, fans are forced to work harder to keep the servers cool. Most of us don’t have the luxury of building a customized, overhead cable trough to hold all our cables. But we can remove abandoned and inoperable cables and make sure that no cables are blocking airflow to each server in the rack. For tips on creating a cleaner and more efficient data center, see Practical Data Center Management.
These are only a handful of tips that will help save energy. What power saving tips can you share with us?
*Picture provided courtesy of Bob Mical