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A Conversation with Jason Hoffman: A systems scientist looks at virtualization, scalability, and Ruby on Rails.

January 1, 2008

Topic: Virtualization

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Mendel Rosenblum, Carl Waldspurger - I/O Virtualization
The term virtual is heavily overloaded, evoking everything from virtual machines running in the cloud to avatars running across virtual worlds. Even within the narrowfigureer context of computer I/O, virtualization has a long, diverse history, exemplified by logical devices that are deliberately separate from their physical instantiations.

Scot Rixner - Network Virtualization: Breaking the Performance Barrier
The recent resurgence in popularity of virtualization has led to its use in a growing number of contexts, many of which require high-performance networking. Consider server consolidation, for example. The efficiency of network virtualization directly impacts the number of network servers that can effectively be consolidated onto a single physical machine. Unfortunately, modern network virtualization techniques incur significant overhead, which limits the achievable network performance. We need new network virtualization techniques to realize the full benefits of virtualization in network-intensive domains.

Ulrich Drepper - The Cost of Virtualization
Virtualization can be implemented in many different ways. It can be done with and without hardware support. The virtualized operating system can be expected to be changed in preparation for virtualization, or it can be expected to work unchanged. Regardless, software developers must strive to meet the three goals of virtualization spelled out by Gerald Popek and Robert Goldberg: fidelity, performance, and safety.

Werner Vogels - Beyond Server Consolidation
Virtualization technology was developed in the late 1960s to make more efficient use of hardware. Hardware was expensive, and there was not that much available. Processing was largely outsourced to the few places that did have computers. On a single IBM System/360, one could run in parallel several environments that maintained full isolation and gave each of its customers the illusion of owning the hardware. Virtualization was time sharing implemented at a coarse-grained level, and isolation was the key achievement of the technology.

Jason Hoffman has a Ph.D. in molecular pathology, but to him the transition between the biological sciences and his current role as CTO of Joyent was completely natural: "Fundamentally, what I’ve always been is a systems scientist, meaning that whether I was studying metabolism or diseases of metabolism or cancer or computer systems or anything else, a system is a system," says Hoffman. He draws on this broad systems background in the work he does at Joyent providing scalable infrastructure for Web applications. Joyent’s cloud-computing infrastructure has become the foundation for many of the increasingly popular applications developed to feed into the social-networking site

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