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P2P Architecture for Self-* Atomic
Memory
Emmanuelle Anceaume Maria Gradinariu Vincent Gramoli
Antonino Virgillito
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Goal
Architecture for Scalable Multi-Reader/Writer Distributed Shared
Memory in P2P Systems
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Roadmap
ApplicationsThere is a solution for each problemModular memory architectureSelf-Healing mechanismTraversing mechanismSelf-Adjusting mechanismConclusion
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Applications
WebServices
Groupware
…w/o cost of maintenance of any centralized control
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Peer-to-Peer (P2P)
Dynamism
Decentralized
Unstructured
Wide-Scale
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Related Problems
Data Availability
Load
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Related Problems
Atomic Consistency
Data Availability
Load
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Dedicated Solutions
Atomic Consistency
Data Availability
LoadSelf-Healing
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Dedicated Solutions
Atomic Consistency
Data Availability
LoadSelf-Healing Self-Adjusting
ISPAN 05 Vincent Gramoli
Dedicated Solutions
Atomic Consistency
Data Availability
Load
Dynamic Quorums*
Self-Healing Self-Adjusting
* Quorums = Mutually intersecting sets
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Modular Approach
Dynamic Quorums
Self-Healing
Self-Adjusting
Traversal Module
Load Balancer Module
Adjuster Module
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Single Object Memory
Atomicity is preserved under object composition.
The memory is obtained by composition of all single object memories.
Some nodes have a copy of the same object X: the object’s replicas.
We refer to those replicas as the memory of object X.
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Adjuster Module
Architecture
Traversal Module
Load Balancer Module
Operation Manager
operation operation-ack
Client
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Logical Overlay
The object’s responsibility is a CAN torus-grid shared by replicas.
Each replica is responsible for a part of a virtual domain space [0,1) x [0,1).
If two zones are adjacent, their responsible are neighbors.
Client
operation
operation-ack
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Bootstrapping ProcessInitially, one replica possessed object X.This is the only responsible of X.
Then X is replicated and responsibility is shared among replicas.
Each replica is responsible for a part of a virtual domain space [0,1) x [0,1).
If two zones are adjacent, their responsible are neighbors.
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Self-Healing
Overlay
failed replica
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Self-Healing
Overlay
Assuming eventual failure detection.
A neighbor becomes responsible of the failed replica’s zone.
The neighbor choice is made by CAN takeover mechanism.
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Traversing
Overlay
Consultation quorum: set of replicas responsible of a whole line.
Propagation quorum: set of replicas responsible of a whole column.
Request receiver
Every propagation quorum intersects every consultation quorum
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Self-Adjusting
Overlay
overloaded replica
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Self-Adjusting
Overlay
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Self-Adjusting
Overlay
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Self-Adjusting
Overlay
Active replication on a node outside
the grid.
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Self-Adjusting
Overlay
underloaded replica
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Self-Adjusting
Overlay
Similar to the self-healing mechanism
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Conclusion
Our approach uses various concepts P2P overlay dynamic quorums replica control
Result Multi-Reader/Writer DSM in P2P Systems Only local information is necessary Fault tolerance is guaranteed Load is balanced Operations are atomic
Future work Using mechanism theory for incentive strategy
