Urs Hölzle (; born 1964) is a
Swiss-American software engineer and technology executive. As
Google
Google LLC (, ) is an American multinational corporation and technology company focusing on online advertising, search engine technology, cloud computing, computer software, quantum computing, e-commerce, consumer electronics, and artificial ...
's eighth employee and its first VP of Engineering, he has shaped much of Google's development processes and infrastructure, as well as its engineering culture.
His most notable contributions include leading the development of fundamental cloud infrastructure such as energy-efficient data centers, distributed compute and storage systems, and software-defined networking. Until July 2023, he was the Senior Vice President of Technical Infrastructure and Google Fellow at Google. In July 2023, he transitioned to being a Google Fellow only.
Career
Before joining Google, Hölzle was an
associate professor
Associate professor is an academic title with two principal meanings: in the North American system and that of the ''Commonwealth system''.
In the ''North American system'', used in the United States and many other countries, it is a position ...
of
computer science
Computer science is the study of computation, information, and automation. Computer science spans Theoretical computer science, theoretical disciplines (such as algorithms, theory of computation, and information theory) to Applied science, ...
at
University of California, Santa Barbara
The University of California, Santa Barbara (UC Santa Barbara or UCSB) is a Public university, public Land-grant university, land-grant research university in Santa Barbara County, California, United States. Tracing its roots back to 1891 as an ...
. He received a master's degree in computer science from
ETH Zurich
ETH Zurich (; ) is a public university in Zurich, Switzerland. Founded in 1854 with the stated mission to educate engineers and scientists, the university focuses primarily on science, technology, engineering, and mathematics. ETH Zurich ran ...
in 1988 and was awarded a
Fulbright
The Fulbright Program, including the Fulbright–Hays Program, is one of several United States cultural exchange programs with the goal of improving intercultural relations, cultural diplomacy, and intercultural competence between the people ...
scholarship that same year. In 1994, he earned a Ph.D. from
Stanford University
Leland Stanford Junior University, commonly referred to as Stanford University, is a Private university, private research university in Stanford, California, United States. It was founded in 1885 by railroad magnate Leland Stanford (the eighth ...
, where his research focused on
programming language
A programming language is a system of notation for writing computer programs.
Programming languages are described in terms of their Syntax (programming languages), syntax (form) and semantics (computer science), semantics (meaning), usually def ...
s and their efficient implementation. Via a startup founded by Hölzle, David Griswold, and
Lars Bak
Lars Ytting Bak (born 16 January 1980) is a Danish former professional road bicycle racer, who rode professionally between 2002 and 2019 for the Fakta, , , , and squads. Since retiring as a rider, Bak has acted as a directeur sportif for in ...
(see
Strongtalk), that work then evolved into a high-performance
Java VM named
HotSpot, acquired by Sun's JavaSoft unit in 1997 and from there became Sun's premier JVM implementation.
In 1999 he joined Google and became its first Vice President of Engineering later that year and influenced Google's corporate and engineering culture.
While he led various areas during the early years of the company, including operations, search, and Gmail, he is best known for his work leading the infrastructure systems underpinning Google's applications, and for their focus on both efficiency and scalability. With
Jeff Dean and
Luiz Barroso he designed the initial distributed architecture for Google. This work was recognized by the Association for Computing Machinery who named him a Fellow for the design, engineering and operation of energy efficient large-scale cloud computing systems. He is also credited for creatin
Google Gulpfor April Fool's Day in 2005.
Data centers and servers
He led the design of Google's efficient data centers which are said to use less than half the power of a conventional data center.
[Google's Green Datacenter](_blank)
/ref> In 2014 he received The Economist's Innovation Award for his datacenter efficiency work.[Economist, December 6, 2014](_blank)
/ref> With Luiz Barroso, he wrote ''The Datacenter as a Computer: An Introduction to the Design of Warehouse-Scale Machines''. Now in its third edition, the book is the most downloaded textbook at Morgan Claypool and is widely used in undergraduate and graduate Computer Science education. For his contributions to the design, operation, and energy efficiency of large-scale data centers, Hölzle was elected into the National Academy of Engineering in 2013.
In June 2007, he introduced the Climate Savers Computing Initiative together with Pat Gelsinger
Patrick Paul Gelsinger (; born March 5, 1961) is an American business executive and engineer, who was the CEO of Intel from February 2021 to December 2024.
Based mainly in Silicon Valley since the late 1970s, Gelsinger graduated from Stanford ...
which aimed to halve the power consumption of desktop computers and servers. In 2012, after mobile computing and enhanced awareness of datacenter energy costs had contributed to significant improvements in energy efficiency, CSCI merged with the Green Grid consortium.
Also in 2007, he and Luiz Barroso wrot
"The Case for Energy Proportional Computing"
which argued that servers should be designed to use power in proportion to their current load, because they spend much of their time being only partially loaded. This paper is often credited for spurring CPU manufacturers to make their designs much more energy efficient. Today, energy proportional computing has become a standard goal for both server and mobile uses.
Networking
Starting in 2005, Hölzle's team began to develop datacenter networking hardware because off-the-shelf network equipment could not scale to the demands of large data centers. Using Clos network
In the field of telecommunications, a Clos network is a kind of multistage circuit-switching network which represents a theoretical idealization of practical, multistage switching systems. It was invented by Edson Erwin in 1938 and first formalize ...
topologies based on commodity switch chips, these datacenter networks scaled from an initial 10 Tbit/s to 1,000 Tbit/s a decade later. today this approach is standard for large datacenter networks; virtually all hyperscale datacenter operators use similar approaches.
In 2012, Hölzle introduced "the G-Scale Network" on which Google had begun managing its petabyte
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable un ...
-scale internal data flow via OpenFlow
OpenFlow is a communications protocol that gives access to the forwarding plane of a network switch or router (computing), router over the network.
Description
OpenFlow enables network controllers to determine the path of network packets across ...
, an open source software system jointly devised by scientists at Stanford and the UC Berkeley and promoted by the Open Networking Foundation. In 2021, this work was recognized by the ACM SIGCOMM Networking Systems Award. The internal data flow, or network, is distinct from the one that connects users to Google services (Search, Gmail, YouTube, etc.). In the process of describing the new network, Hölzle also confirmed more about Google's making of its own networking equipment like routers and switches
In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type o ...
for G-Scale; and said the company wanted, by being open about the changes, to "encourage the industry — hardware, software and ISP's — to look down this path and say, 'I can benefit from this.'" He said network utilization was nearing 100% of capacity, a dramatic efficiency improvement.
Google's teams also heavily contributed to software-defined networking
Software-defined networking (SDN) is an approach to network management that uses abstraction to enable dynamic and programmatically efficient network configuration to create grouping and segmentation while improving network performance and monit ...
, creating or contributing to key building blocks used in many networks today, includin
OpenConfig
for vendor-neutral, model-driven network management; gRPC
gRPC (acronym for gRPC Remote Procedure Calls) is a cross-platform high-performance remote procedure call (RPC) framework. gRPC was initially created by Google, but is open source and is used in many organizations. Use cases range from microservi ...
for fast RPCs, protobuf for data interchange
OpenTelemetry
for tracing, and th
Istio
service mesh.
Cloud computing
Hölzle is credited with leading the creation of Google's internal cloud, including architecting clusters based on commodity servers, distributed file systems, cluster scheduling, software defined networking, hardware reliability, processor design, custom ASICs for AI ( TPUs) and vide processing, and many more. One of the most notable events from this period was the emergence of Kubernetes
Kubernetes (), also known as K8s is an open-source software, open-source OS-level virtualization, container orchestration (computing), orchestration system for automating software deployment, scaling, and management. Originally designed by Googl ...
, a project funded by Hölzle.
Google's internal cloud doesn't use virtualization, but product development on an external cloud platform started in 2014, leading to the launch of the Google Cloud Platform
Google Cloud Platform (GCP) is a suite of cloud computing services offered by Google that provides a series of modular cloud services including computing, Computer data storage, data storage, Data analysis, data analytics, and machine learnin ...
in 2016. Hölzle is also credited with changing Google Cloud's engineering culture "to make the transition from niche cloud to enterprise class cloud".
Environmental work
In 2007, Hölzle announced that Google would be carbon neutral starting that year, using individually selected and monitored carbon offset
Carbon offsetting is a carbon trading mechanism that enables entities to compensate for offset greenhouse gas emissions by investing in projects that reduce, avoid, or remove emissions elsewhere. When an entity invests in a carbon offsetting ...
projects. In the same year, Google started the REsolar thermal
Solar thermal energy (STE) is a form of energy and a technology for harnessing solar energy to generate thermal energy for use in Industrial sector, industry, and in the residential and commercial sectors. Solar thermal collectors are classified ...
) because it was not keeping pace with the rapid price decline of another solar technology –
.
Starting in 2010, Google began buying renewable energy from new wind and solar farms to cover the energy needs for all its datacenters. In 2017, Hölzle received th
"for bringing about innovations and radical efficiencies in data center technology and increasing corporate purchasing of renewable energy" and for "not only accelerating Google’s sustainability,
also cutting a path for other companies to follow suit.” While purchases initially were small, they created a market for corporate renewable energy purchases that has become very influential in driving the overall growth of renewable energy purchases. For example, SP Global reports that the top
(Amazon, Google, Meta, Microsoft) accounted for over 40% of contracted capacity during 2017-22.
In 2017 Google reached enough renewable energy to offset 100% of its usage and now is the world's largest corporate buyer of renewable energy. After reaching 100% renewables at an annual average level, Google has pursued an additional focus on 24/7 carbon free energy, i.e., actually running on 100% renewable energy every hour of every day. As of 2022, seven Google datacenter regions reached 90% or more carbon-free energy, and thirteen reached more than 85%. Hölzle has widely been credited for favoring market based approaches, discouraging proprietary paths that would only benefit Google. As a result, organizations like th
now focus on enabling any company to pursue their own carbon-free energy goals.
In 2022, Hölzle was revealed as the primary investor behind the New Zealand based solar developer Helios which aims to build about 10 grid-connected solar farms across New Zealand.
He is a board member of the
.
in 2013 for contributions to the design, operation, and energy efficiency of large-scale data centers.