P2P Architecture for Self-* Atomic Memory

1
P2P Architecture for Self- Atomic
Memory

• Emmanuelle Anceaume
• Maria Gradinariu
• Vincent Gramoli
• Antonino Virgillito

2
Goal

• Architecture for Scalable Multi-Reader/Writer
  Distributed Shared Memory in P2P Systems

3
Roadmap

• Applications
• There is a solution for each problem
• Modular memory architecture
• Self-Healing mechanism
• Traversing mechanism
• Self-Adjusting mechanism
• Conclusion

4
Applications

• WebServices
• Groupware

w/o cost of maintenance of any centralized
control
5
Peer-to-Peer (P2P)

• Dynamism
• Decentralized
• Unstructured
• Wide-Scale

6
Related Problems
Data Availability
Load
7
Related Problems
Atomic Consistency
Data Availability
Load
8
Dedicated Solutions
Atomic Consistency
Self-Healing
Data Availability
Load
9
Dedicated Solutions
Atomic Consistency
Self-Healing
Self-Adjusting
Data Availability
Load
10
Dedicated Solutions
Dynamic Quorums
Atomic Consistency
Self-Healing
Self-Adjusting
Data Availability
Load
Quorums Mutually intersecting sets
11
Modular Approach
Traversal Module
Dynamic Quorums
Load Balancer Module
Self-Healing
Adjuster Module
Self-Adjusting
12
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
  objects replicas.
• We refer to those replicas as the memory of
  object X.

13
Architecture
Client
operation
operation-ack
Operation Manager
Traversal Module
Load Balancer Module
Adjuster Module
14
Logical Overlay








The objects 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.
operation
Client
operation-ack
15
Bootstrapping Process
Initially, 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.


























16
Self-Healing








failed replica
Overlay
17
Self-Healing








Assuming eventual failure detection. A neighbor
becomes responsible of the failed replicas
zone. The neighbor choice is made by CAN
takeover mechanism.
Overlay
18
Traversing








Consultation quorum set of replicas responsible
of a whole line.
Request receiver
Every propagation quorum intersects every
consultation quorum
Propagation quorum set of replicas responsible
of a whole column.
Overlay
19
Self-Adjusting








overloaded replica
Overlay
20
Self-Adjusting








Overlay
21
Self-Adjusting








Overlay
22
Self-Adjusting









Active replication on a node outside the grid.
Overlay
23
Self-Adjusting








underloaded replica
Overlay
24
Self-Adjusting








Similar to the self-healing mechanism
Overlay
25
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