How we’re making Cloudflare’s infrastructure more sustainable

Whether you are building a global network or buying groceries, some rules of sustainable living remain the same: be thoughtful about what you get, make the most out of what you have, and try to upcycle your waste rather than throwing it away. These rules are central to Cloudflare — we take helping build a better Internet seriously, and we define this as not just having the most secure, reliable, and performant network — but also the most sustainable one.

With incredible growth of the Internet, and the increased usage of Cloudflare’s network, even linear improvements to sustainability in our hardware today will result in exponential gains in the future. We want to use this post to outline how we think about the sustainability impact of the hardware in our network, and what we’re doing to continually mitigate that impact.

The total carbon footprint of a server is approximately 6 tons of Carbon Dioxide equivalent (CO2eq) when used in the US. There are four parts to the carbon footprint of any computing device:

1. The embodied emissions: source materials and production

2. Packing and shipping

3. Use of the product

4. End of life.

The emissions from the actual operations and use of a server account for the vast majority of the total life-cycle impact. The secondary impact is embodied emissions (which is the carbon footprint from the creation of the device in the first place), which is about 10% overall.

It’s difficult to reduce the total emissions for the operation of servers. If there’s a workload that needs computing power, the server will complete the workload and use the energy required to complete it. What we can do, however, is consistently seek to improve the amount of computing output per kilo of CO2 emissions — and the way we do that is to consistently upgrade our hardware to the most power-efficient designs. As we switch from one generation of server to the next, we often see very large increases in computing output, at the same level of power consumption. In this regard, given energy is a large cost for our business, our incentives of reducing our environmental impact are naturally aligned to our business model.

The other large category of emissions — the embodied emissions — are a domain where we actually have a lot more control than the use of the product. Reminder from before: the embodied carbon means the sources of emissions generated outside of equipments' operation. How can we reduce the embodied emissions involved in running a fleet of servers? Turns out, there are a few ways: modular design, relying on open vs proprietary standards to enable reuse, and recycling.

Modular Design

The first big opportunity is through modular system design. Modular systems are a great way of reducing embodied carbon, as they result in fewer new components and allow for parts that don’t have efficiency upgrades to be leveraged longer. Modular server design is essentially decomposing functions of the motherboard onto sub-boards so that the server owner can selectively upgrade the components that are required for their use cases.

How much of an impact can modular design have? Well, if 30% of the server is delivering meaningful efficiency gains (usually CPU and memory, sometimes I/O), we may really need to upgrade those in order to meet efficiency goals, but creating an additional 70% overhead in embodied carbon (i.e. the rest of the server, which often is made up of components that do not get more efficient) is not logical. Modular design allows us to upgrade the components that will improve the operational efficiency of our data centers, but amortize carbon in the “glue logic” components over the longer time periods for which they can continue to function.

Previously, many systems providers drove ridiculous and useless changes in the peripherals (custom I/Os, outputs that may not be needed for a specific use case such as VGA for crash carts we might not use given remote operations, etc.), which would force a new motherboard design for every new CPU socket design. By standardizing those interfaces across vendors, we can now only source the components we need, and reuse a larger percentage of systems ourselves. This trend also helps with reliability (sub-boards are more well tested), and supply assurance (since standardized subcomponent boards can be sourced from more vendors), something all of us in the industry have had top-of-mind given global supply challenges of the past few years.

Standards-based Hardware to Encourage Re-use

But even with modularity, components need to go somewhere after they’ve been deprecated — and historically, this place has been a landfill. There is demand for second-hand servers, but many have been parts of closed systems with proprietary firmware and BIOS, so repurposing them has been costly or impossible to integrate into new systems. The economics of a circular economy are such that service fees for closed firmware and BIOS support as well as proprietary interconnects or ones that are not standardized can make reuse prohibitively expensive. How do you solve this? Well, if servers can be supported using open source firmware and BIOS, you dramatically reduce the cost of reusing the parts — so that another provider can support the new customer.

Recycling

Beyond that, though, there are parts failures, or parts that are simply no longer economical to be run, even in the second hand market. Metal recycling can always be done, and some manufacturers are starting to invest in programs there, although the energy investment for extracting the usable elements sometimes doesn’t make sense. There is innovation in this domain, Zhan, et al. (2020) developed an environmentally friendly and efficient hydrothermal-buffering technique for the recycling of GaAs-based ICs, achieving gallium and arsenic recovery rates of 99.9 and 95.5% respectively. Adoption is still limited — most manufacturers are discussing water recycling and renewable energy vs. full-fledged recycling of metals — but we’re closely monitoring the space to take advantage of any further innovation that happens.

It is great to talk about these concepts, but we are doing this work today. I’d describe them as being under two main banners: taking steps to reduce embodied emissions through modular and open standards design, and also using the most power-efficient solutions for our workloads.

Our next generation of servers, Gen 12, will be coming soon. We’re emphasizing modular-driven design, as well as a focus on open standards, to enable reuse of the components inside the servers.

A modular-driven design

Historically, every generation of server here at Cloudflare has required a massive redesign. An upgrade to a new CPU required a new motherboard, power supply, chassis, memory DIMMs, and BMC. This, in turn, might mean new fans, storage, network cards, and even cables. However, many of these components are not changing drastically from generation to generation: these components are built using older manufacturing processes, and leverage interconnection protocols that do not require the latest speeds.

To help illustrate this, let’s look at our Gen 11 server today: a single socket server is ~450W of power, with the CPU and associated memory taking about 320W of that (potentially 360W at peak load). All the other components on that system (mentioned above) are ~100W of operational power (mostly dominated by fans, which is why so many companies are exploring alternative cooling designs), so they are not where the optimization efforts or newer ICs will greatly improve the system’s efficiency. So, instead of rebuilding all those pieces from scratch for every new server and generating that much more embodied carbon, we are reusing them as often as possible.

By disaggregating components that require changes for efficiency reasons from other system-level functions (storage, fans, BMCs, programmable logic devices, etc.), we are able to maximize reuse of electronic components across generations. Building systems modularly like this significantly reduces our embodied carbon footprint over time. Consider how much waste would be eliminated if you were able to upgrade your car's engine to improve its efficiency without changing the rest of the parts that are working well, like the frame, seats, and windows. That's what modular design is enabling in data centers like ours across the world.

A Push for Open Standards, Too

We, as an industry, have to work together to accelerate interoperability across interfaces, standards, and vendors if we want to achieve true modularity and our goal of a 70% reduction in e-waste. We have begun this effort by leveraging standard add-in-card form factors (OCP 2.0 and 3.0 NICs, Datacenter Secure Control Module for our security and management modules, etc.) and our next server design is leveraging Datacenter Modular Hardware System, an open-source design specification that allows for modular subcomponents to be connected across common buses (regardless of the system manufacturer). This technique allows us to maintain these components over multiple generations without having to incur more carbon debt on parts that don’t change as often as CPUs and memory.

In order to enable a more comprehensive circular economy, Cloudflare has made extensive and increasing use of open-source solutions, like OpenBMC, a requirement for all of our vendors, and we work to ensure fixes are upstreamed to the community. Open system firmware allows for greater security through auditability, but the most important factor for sustainability is that a new party can assume responsibility and support for that server, which allows systems that might otherwise have to be destroyed to be reused. This ensures that (other than data-bearing assets, which are destroyed based on our security policy) 99% of hardware used by Cloudflare is repurposed, reducing the number of new servers that need to be built to fulfill global capacity demand. Further details about the specifics of how that happens – and how you can join our vision of reducing e-waste – you can find in this blog post.

The other big way we can push for sustainability (in our hardware) while responding to our exponential increase in demand without wastefully throwing more servers at the problem is simple in concept, and difficult in practice: testing and deploying more power-efficient architectures and tuning them for our workloads. This means not only evaluating the efficiency of our next generation of servers and networking gear, but also reducing hardware and energy waste in our fleet.

Currently, in production, we see that Gen 11 servers can handle about 25% more requests than Gen 10 servers for the same amount of energy. This is about what we expected when we were testing in mid-2021, and is exciting to see given that we continue to launch new products and services we couldn’t test at that time.

System power efficiency is not as simple a concept as it used to be for us. Historically, the key metric for assessing efficiency has been requests per second per watt. This metric allowed for multi-generational performance comparisons when qualifying new generations of servers, but it was really designed with our historical core product suite in mind.

We want – and, as a matter of scaling, require – our global network to be an increasingly intelligent threat detection mechanism, and also a highly performant development platform for our customers. As anyone who’s looked at a benchmark when shopping for a new computer knows, fast performance in one domain (traditional benchmarks such as SpecInt_Rate, STREAM, etc.) does not necessarily mean fast performance in another (e.g. AI inference, video processing, bulk object storage). The validation testing process for our next generation of server needs to take all of these workloads and their relative prevalence into account — not just requests. The deep partnership between hardware and software that Cloudflare can have is enabling optimization opportunities that other companies running third party code cannot pursue. I often say this is one of our superpowers, and this is the opportunity that makes me most excited about my job every day.

The other way we can be both sustainable and efficient is by leveraging domain-specific accelerators. Accelerators are a wide field, and we’ve seen incredible opportunities with application-level ones (see our recent announcement on AV1 hardware acceleration for Cloudflare Stream) as well as infrastructure accelerators (sometimes referred to as Smart NICs). That said, adding new silicon to our fleet is only adding to the problem if it isn’t as efficient as the thing it’s replacing, and a node-level performance analysis often misses the complexity of deployment in a fleet as distributed as ours, so we’re moving quickly but cautiously.

We’re pushing by ourselves as hard as we can, but there are certain areas where the industry as a whole needs to step up.

In particular: there is a woeful lack of standards about emissions reporting for server component manufacturing and operation, so we are engaging with standards bodies like the Open Compute Project to help define sustainability metrics for the industry at large. This post explains how we are increasing our efficiency and decreasing our carbon footprint generationally, but there should be a clear methodology that we can use to ensure that you know what kind of businesses you are supporting.

The Greenhouse Gas (GHG) Protocol initiative is doing a great job developing internationally accepted GHG accounting and reporting standards for business and to promote their broad adoption. They define scope 1 emissions to be the “direct carbon accounting of a reporting company’s operations” which is somewhat easy to calculate, and quantify scope 3 emissions as “the indirect value chain emissions.” To have standardized metrics across the entire life cycle of generating equipment, we need the carbon footprint of the subcomponents’ manufacturing process, supply chains, transportation, and even the construction methods used in building our data centers.

Ensuring embodied carbon is measured consistently across vendors is a necessity for building industry-standard, defensible metrics.

The carbon impact of the cloud has a meaningful impact on the Earth–by some accounts, the ICT footprint will be 21% of global energy demand by 2030. We’re absolutely committed to keeping Cloudflare’s footprint on the planet as small as possible. If you’ve made it this far through, and you’re interested in contributing to building the most global, efficient, and sustainable network on the Internet — the Hardware Systems Engineering team is hiring. Come join us.