SAM is a project aiming at providing wide-scale storage system. With the growth of the Internet these past decades, it has become a real treasure of resources accessible from almost any computer around the world. Resource has several meanings: information archived in text format, numerical music that are shared and sold, images that are accessed by many users, auctions, etc. Typically, those resources might be accessed many times during a quite short period of time.

The solution SAM brings, is to take benefit from the resources shared to provide quality of service, rapidity, scalability at any time. While its solicitation grows with the number of users, its capability grows accordingly. A user can access and modify data which makes any application possible on top of SAM.


  1. Introduction

    The name of our solution means Self* Atomic Memory for P2P Systems. First of all, this high level abstract system is composed by a set of individual participants. Those participants share an object among the others. This object can be accessed through read and write operations by all the users. This makes consultation, copy, modification and backup possible. Second our algorithm provides self* capabilities. That is regarding to some system behaviors, the system adapts its own size: it can take the decision to shrink itself or to expand itself on-the-fly and as needed. SAM is also able to self-detect failures from part of its element and repair itself accordingly in order to guarantee a Quality of Service (QoS).

  2. Why?

    This idea comes from the following observation. In wide-scale systems, the load implied by client request must involved high replication of the objects. To balance the load, the size of the atomic memory grow regarding to the number of replicas. Hence it becomes costly to notify clients about the constantly changing structure. Since fault tolerance and more generally dynamism requires reconfiguration, reconfiguration is expected to be frequent and becomes a key process in the protocol complexity. Therefore reconfiguration has to involve low cost in term of time and message complexity. For this purpose, our approach uses only local reconfiguration which heals the system rapidly. It also provides adaptive operation, in order to make reconfiguration with constant-bounded complexity.

  3. Applications

    The application can be found in several domains such as webservices and groupware.

    Groupware: As long as a file can be modified/updated in a system with atomicity guarantee, it is possible for many users to participate in its enhancement. Therefore SAM makes joint work achievable. Wikipedia is a centralized example of what collective intelligence is able to provide. SAM provides solution to the congestion involved in such case.

    WebServices: eBay is an online auction service. It is a good example of an application making the write primitive fundamental. It serves users that want either to sell or to buy stuff of any kind. The distributed aspect of SAM provides a service letting peers contacting themselves without paying extra for a sever maintenance.

  4. Team

    The ADEPT Team of IRISA is dedicated to algorithms for dependable systems. Some members of the team, all working on problem related to dynamism, focus on this project since the beginning of 2005. The algorithm has been discovered during April 05 [1]. It appears with symmetrical two-phases read and write operations in [2]. Because of the high cost (in time) of read/write operations, an improvement have been proposed in [3], that makes the read operation shorter. The drawback is to let writes locking two time faster reads during a really small period of time.

    1. Researchers
      • Emmanuelle Anceaume
      • Maria Gradinariu
    2. PhD Student
      • Vincent Gramoli
    3. Postdoctoral associate
      • Antonino Virgillito
    4. Internship students
      • Sylvestre Cozic
      • Romaric Ludinard

  5. References

    SAM: Self* Atomic Memory for P2P Systems
    Emmanuelle Anceaume, Maria Gradinariu, Vincent Gramoli, Antonino Virgillito
    Technical Report n1717 - IRISA / INRIA Rennes
    June 2005  file bib

    Mémoire atomique auto-reconfigurable pour Systèmes P2P
    Vincent Gramoli
    Manifestation des jeunes chercheurs francophones dans les domaines des STIC
    Nov. 2005  bib

    P2P Architecture for Self-* Atomic Memory
    Emmanuelle Anceaume, Maria Gradinariu, Vincent Gramoli, Antonino Virgillito
    International Symposium on Parallel Architectures, Algorithms and Networks
    Dec. 2005  bib

Work supported by IRISA / INRIA Rennes