Wednesday, 16/5/12, 11:30

CS, Taub 337
 

Dynamic Reconfiguration of Primary/Backup Clusters
 

 

Dynamically changing (reconfiguring) the membership of a replicated distributed system while preserving data consistency and system availability is a challenging problem. In this talk I will discuss this problem in the context of Primary/Backup clusters and Apache Zookeeper. Zookeeper is an open source system which enables highly reliable distributed coordination. It is widely used in industry, for example in Yahoo!, Facebook,Twitter, VMWare, Box, Cloudera, Mapr, UBS, Goldman Sachs, Nicira, Netflix and many others. A common use-case of Zookeeper is to dynamically maintain membership and other configuration metadata for its users. Zookeeper itself is a replicated distributed system. Unfortunately, the membership and all other configuration parameters of Zookeeper are static – they're loaded during boot and cannot be altered. Operators resort to ''rolling restart'' – a manually intensive and error-prone method of changing the configuration that has caused data loss and inconsistency in production. Automatic reconfiguration functionality has been requested by operators since 2008. Several previous proposals were found incorrect and rejected. We designed and implemented a new reconfiguration protocol in Zookeeper and are currently integrating it into the codebase. It fully automates configuration changes: the set of Zookeeper servers, their roles, addresses, etc. can be changed dynamically, without service interruption and while maintaining data consistency. By leveraging the properties already provided by Zookeeper our protocol is considerably simpler than state of the art in reconfiguration protocols. Our protocol also encompasses the clients — clients are rebalanced across servers in the new configuration, while keeping the extent of migration proportional to the change in membership.

This is a joint work with Benjamin Reed (Yahoo!), Dahlia Malkhi (MSR) and Flavio Junqueira (Yahoo!). A paper describing this work will appear in the 2012 Usenix ATC conference and in the 2012 Hadoop Summit. http://www.cs.technion.ac.il/~shralex/zkreconfig.pdf

 

Bio: Alexander (Alex) Shraer is a Research Scientist in Yahoo!. His research interests include large-scale and dynamic distributed systems, various aspects of fault-tolerance, secure cloud storage, publish-subscribe systems, etc. Alex received his B.Sc. (2004, summa cum laude) and M.Sc. (2006, cum laude) degrees in Computer Science and PhD in Electrical Engineering (2010) from the Technion, Israel. He is a recipient of the Levi Eshkol 3-year PhD fellowship, awarded by the Israeli Ministry of Science.

 

Hugo Krawczyk (IBM Research)

Hovav Shacham (UCSD)

 

 

 

In this talk, we present techniques to enable green communications in future generation of wireless systems that will rely on cooperation and cognition to meet increasing demand of high data rate. So far, achieving high data rate has been the primary focus of research in cooperative and CR systems, without much consideration of energy efficiency. However, many of these techniques significantly increase system complexity and energy consumption. Escalating energy costs and environmental concerns have already created an urgent need for more energy-efficient "green" wireless communications. Therefore, we need to design energy-efficient solutions for cooperative and cognitive networks, which will potentially drive the future generation of wireless communication. We focus on several important topics that are crucial towards reducing the energy consumption of the cognitive and cooperative networks. These topics include efficient base station redesign, heterogeneous network deployment, green communications via cognitive radio, cooperative relays to deliver green communications, and energy efficient cognitive cooperative networks.

 

Vijay has served on the Board of Governors of the IEEE Information Theory Society and the IEEE Communications Society. He has held important positions in these societies and has organized conferences such as ISIT'83, ISIT'95, ICC'99 and VTC 2002 Fall. He played a major role in the creation of the IEEE Transactions on Wireless Communications, and served as its editor-in-chief during 2007, 2008 and 2009. He is a past President of the IEEE Information Theory Society and is currently serving as the President of the IEEE Communications Society.

 

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Title:  Consistent Hashing, Danny Lewin, and the Creation of Akamai

 

Speaker: Tom Leighton, MIT Prof of Applied Math, Co-founder and Chief Scientist at Akamai Technologies

 

 

In 1996, twelve years after making Aliyah to Israel, Danny Lewin graduated from the Technion and came to MIT to study algorithms.  Over the next few years, he wrote a prize-winning Master’s Thesis on Consistent Hashing and co-founded Akamai Technologies, which today accelerates the delivery of over 250,000 web sites, including all of the top media and commerce brands on the Web. 

 

In this talk, we will describe some of Danny’s early work on consistent hashing and how such theoretical work on algorithms ultimately led to the creation of an S&P 500 company for accelerating and securing web applications.  We will also describe some of the scalability and security challenges that the internet is facing today, and Akamai’s vision for addressing those challenges.

 

Akamai is headquartered in Cambridge, MA, and through its recent acquisition of Cotendo Networks, Akamai now operates a significant and growing R&D center in Tel Aviv.

 

Tuesday, 13.3.2012 at 14:30 in room 861

Electrical Engineering Building, Technion

 

Providing higher performance than state-of-the-art embedded processors can deliver today will increase safety, comfort, number and quality of services, while also lowering emissions as well as fuel demands for automotive, avionic and automation applications. Engineers who design hard real-time embedded systems in such embedded domains express a need for several times the performance available today while keeping safety as major criterion. A breakthrough in performance is expected by parallelising hard real-time applications and running them on an embedded multi-core processor, which enables combining the requirements for high-performance with time-predictable execution. 

The talk will discuss results of the EC FP-7 project MERASA (Multi-Core Execution of Hard Real-Time Applications Supporting Analysability, 2007-2011) and objectives of the parMERASA project (Multi-Core Execution of Parallelised Hard Real-Time Applications Supporting Analysability, 2011-2014). Both projects target timing analysable systems of parallel hard real-time applications running on a scalable multi-core processor. MERASA delivered a fully timing analysable four-core SMT processor as FPGA prototype together with adapted system software and WCET tools, running a parallelised version of a Honeywell International autonomous flying vehicle code as demonstrator. parMERASA shifts its objectives even more towards parallelisation of hard real-time application software. To this end application companies of avionics, automotive, and construction machinery domains cooperate with tool developers and multi-core architects.

Affiliation: Toyota Technological Institute and University of Chicago

Date: Wednesday, 29.2.2012, 14:30

Place: Room 337-8 Taub Bld