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SAM
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.
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![irisa](../img/irisa.gif)
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- 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).
- 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.
- Applications
The application can be found in several domains such as webservices and groupware.
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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.
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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.
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- 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.
- Researchers
- Emmanuelle Anceaume
- Maria Gradinariu
- PhD Student
- Postdoctoral associate
- Internship students
- Sylvestre Cozic
- Romaric Ludinard
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 |
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