[PPT] - A Simulation-based Evaluation of a Hybrid Storage System combining PowerPoint Presentation

SLIDE 1

. .

A Simulation-based Evaluation of a Hybrid Storage System combining P2P, F2F, and Cloud storage with a Distributed Reputation System

Anders Skoglund

andsk668@student.liu.se

November 04, 2013

SLIDE 2

. . Storage methods

Cloud storage P2P storage F2F storage Hybrid storage + reputation system

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

SLIDE 3

. . Storage methods

Cloud storage

Advantages

+ Scalable + High availability + Contractual accountability

Disadvantages

− Cost − Possible single point of failure

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

SLIDE 4

. . Storage methods

P2P storage

Advantages

+ Large number of peers + Scalable + No single point of failure + Cooperative / low cost

Disadvantages

− Semi-anonymous peers − No accountability − Peers can’t be trusted

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

SLIDE 5

. . Storage methods

F2F storage

Advantages

+ No single point of failure + Cooperative / low cost + Social accountability + Known and trusted peers

Disadvantages

− Few peers − Possible availability issues

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

SLIDE 6

. . Storage methods

Hybrid storage + reputation system

Advantages

+ Scalable + Trusted friend peers + Predictable peer behavior + No single point of failure + Cooperative / low cost

Disadvantages

− ?

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

SLIDE 7

. . System Overview

Components

DHT Distributed search Block distributor Reputation system

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

SLIDE 8

. . Reputation systems

Simple reputation systems

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

SLIDE 9

. . Reputation systems

Distributed reputation systems

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

1.0 1.0 1.0 1.0 0.3 0.0 0.1 0.3 0.5 1.0 1.0 0.5 1.0 1.0 1.0 1.0

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

SLIDE 10

. . Reputation systems

EigenTrust

Algorithm 1 BasicEigenTrust

C : Local trust matrix. # » p : Vector of relative trust values for all pre-trusted peers. # » t : Vector of global trust values for all peers. a : Weight given to pre-trusted peers when computing global trust. ϵ : Threshold used to stop the algorithm once it converges. 1: function ComputeTrust(C) 2: # » t 0 ← # » p 3: k ← 0 4: repeat 5: # » t k+1 ← (1 − a)CT # » t k + a# » p 6: δ ← ||# » t k+1 − # » t k|| 7: k ← k + 1 8: until δ < ϵ 9: return # » t k 10: end function

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

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. . Reputation systems

Distributed EigenTrust

Algorithm 2 SecureEigenTrust

C : Local trust matrix. # » p : Vector of relative trust values for all pre-trusted peers. # » t : Vector of global trust values for all peers. Ad : Peers that have reported local trust values about a daughter peer d. Bd : Peers that a daughter peer d has reported local trust values about. D : Daughter peers of the score manager. Mi : All score managers for the peer i. a : Weight given to pre-trusted peers when computing global trust. ϵ : Threshold used to stop the algorithm once it converges. 1: function ComputeTrust(C) 2: for each d ∈ D do 3: Ad ← ServedByDaughter(d) 4: Bd ← HasServedDaughter(d) 5: k ← 0 6: for each j ∈ Ad do 7: cjd ← QueryLocalTrust(Hash(j)) 8: end for 9: repeat 10: tk+1

d

← (1 − a) ∑n

j=1 cjdtk j + apd

11: for each j ∈ Bd do 12: Mj ← Hash(j) 13: SendLocalTrust(cdj, Mj) 14: SendGlobalTrust(tk+1

d

, Mj) 15: end for 16: for each j ∈ Ad do 17: Mj ← Hash(j) 18: cjd ← RecieveLocalTrust(Mj) 19: tk+1

j

← RecieveGlobalTrust(Mj) 20: end for 21: k ← k + 1 22: until |tk+1

d

− tk

d| < ϵ

23: end for 24: end function

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

SLIDE 12

. . Reputation systems

EigenTrust sij = sat(i, j) − unsat(i, j) cij = {

max(sij,0) ∑

j max(sij,0),

if ∑

j max(sij) ̸= 0

pj,

therwise

pi = {

1 |P|,

if i ∈ P 0, if i / ∈ P tj = (1 − a) ∑

i

cijti + apj + Simple + Well analyzed + Scalable − Very simple trust model − Relative trust values

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A Simulation-based Evaluation of a Hybrid Storage System

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. . Reputation systems

Modified EigenTrust sij = {

sat(i,j) sat(i,j)+unsat(i,j),

if sat(i, j) + unsat(i, j) ̸= 0 0,

therwise

cij = sij tj = {∑

i cijwij,

if j / ∈ P 1, if j ∈ P wij = ti ∑

k∈Aj tk

Computes more useful trust values than EigenTrust Can use the same distributed algorithms as EigenTrust

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

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. . Reputation systems

Global trust

1.0 1.0 0.5 1.0 1.0 1.0 1.0 0.1 1.0 1.0 1.0 1.0 0.0 0.3 0.5 0.5 1.0 0.0 0.0 0.0 0.1 0.1 1.0 1.0 1.0 1.0 1.0 1.0 0.1 1.0 0.5 0.0 0.0 0.0 1.0 1.0 0.0 1.0 0.1 0.0 0.1 0.0 0.1 0.0 1.0 0.0 0.0 0.0 0.1 1.0 1.0 0.0 0.0 1.0 0.0 0.5 0.5 0.1 1.0 0.0 1.0 1.0 0.1 0.3 0.0 0.1 1.0 0.0 0.3 1.0 0.0 1.0 0.1 0.0 1.0 1.0 1.0 1.0 0.5 0.0 0.0 0.0 1.0 1.0 0.0 0.3 0.0 0.1 0.3 0.5 1.0 0.5 0.1 1.0 1.0 1.0 0.0 0.0 0.1 0.5 0.0 0.1 0.0 0.0 1.0 0.0 0.0 0.5 1.0 0.1 1.0 0.0 1.0 1.0 0.0 0.1 0.1 1.0 0.0 1.0 0.0 1.0 1.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 0.1 1.0 0.0 0.1 1.0 0.5 0.0 1.0 0.0 1.0 0.5 0.0 1.0 0.0 1.0 1.0 0.1 0.0 0.0 0.5 0.0 0.0

1.0

0.0 0.0

0.3 0.0 0.1

0.3

0.5 1.0 0.5 0.1

1.0 1.0

0.0

0.0 0.1 0.1 0.5 0.0 0.0 0.1 1.0 1.0 1.0 0.1 0.0 0.0 1.0 1.0 0.1 0.0 0.1 0.0 0.1 1.0 0.0 0.0 1.0 0.0 0.0 1.0 0.0 0.0 0.0 0.5 1.0 1.0 1.0 1.0 0.1 0.1 0.0 0.5 0.0 0.0 0.1 1.0 1.0 0.0 0.0 1.0 0.1 0.0 0.1 0.0 0.0 1.0 0.0 0.0 1.0 0.0 0.0 1.0 0.1 1.0 0.0 0.1 0.5 1.0 0.5 0.0 1.0

0.0 0.1

0.3 0.5 1.0 0.5 1.0 1.0 1.0 0.3 1.0 0.0 0.0

0.1

1.0 0.5

0.0

0.3 1.0 0.0 1.0 0.0 0.5 1.0 0.5 1.0 1.0 0.3 1.0 0.0 0.0 0.1 1.0 0.5 0.5 0.0 0.3 0.3 0.0 0.1 0.5 0.1 0.1 0.1 1.0 0.3 0.5 0.0 0.0

0.0 0.0

0.1 1.0 1.0 0.1 1.0 0.5 0.0 0.0 0.0 0.5

0.0

1.0 0.0 0.0 0.1 0.0 0.0 0.1 0.3

0.5 1.0 1.0

1.0

0.5

0.1 1.0 0.0 0.1 0.3 1.0 0.0 1.0

0.0 0.1 0.5

1.0 1.0 1.0 1.0 0.1

1.0 0.0

0.0

0.1 1.0 0.0 1.0

0.0 0.5 0.0 1.0 0.0 0.0 0.1 0.0 0.0 0.5 1.0 0.5 1.0 0.1 0.3 0.5 0.0 1.0 1.0 0.1 0.1 0.0 1.0 0.0 0.0 0.3 0.0 0.1 0.3 0.0 0.1 0.3 1.0 0.5 0.3 1.0 0.0 0.5 0.1 0.5 0.0 1.0 0.0 1.0 0.1 0.3 0.5 0.0 1.0 1.0 0.1 0.1 0.0 1.0 0.0 0.0 0.3 0.5 1.0 1.0 0.0 1.0 0.0 0.3 0.0 1.0 1.0 0.3 0.0 0.1 0.3 0.5 0.5 1.0 1.0 1.0 1.0 0.1 0.1 0.1 1.0 1.0 1.0 1.0 0.0 0.3 0.5 0.5 1.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.1 1.0 1.0 1.0 1.0 0.5 1.0 0.1 1.0 0.5 1.0 1.0 0.1 0.0 0.1 0.0 0.1 0.0 0.0 0.1 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.5 0.5 0.1 1.0 0.0 1.0 0.3 1.0 1.0 1.0 1.0 0.5 0.0 0.0 0.0 0.0 0.3 0.0 0.1 0.3 0.1 1.0 0.0 0.1 0.1 0.0 0.0 1.0 1.0 1.0 0.1 0.1 0.0 0.5 0.0 0.0 0.0 0.0 0.1 1.0 1.0 1.0 0.1 0.0 0.0 1.0 0.1 0.0 0.1 0.0 1.0 0.0 0.0 0.1 1.0 0.1 0.0 0.0 1.0 1.0 0.0 0.5 0.0 1.0 0.0 0.5 1.0 0.5 1.0 0.5 0.3 0.1 0.0 1.0 0.0 0.0 0.3 0.3 1.0

1.0

0.3 0.0 0.1 0.3 0.5 1.0 0.1 0.1 1.0 1.0

1.0 0.0

0.0

0.5

0.5 0.0

0.0

0.0 0.0 0.0 0.0 0.0 0.0 0.1

1.0

1.0 1.0 1.0 0.5 1.0 1.0 0.0 0.0

1.0 1.0 1.0

0.0 0.0 0.1 1.0 1.0 1.0

0.0

0.0 0.1 1.0 1.0 1.0 0.5 0.1 1.0 1.0 0.0 0.1 1.0 0.5 0.0 0.0 0.0 0.3 0.0 0.1 0.3 0.1 0.0 0.5 1.0 1.0

0.1

0.0 0.0 0.0 0.0

0.0

0.1 1.0 1.0 1.0 0.1 0.0 0.1 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 0.0 0.0 0.5 1.0 0.1 1.0 1.0 0.1 0.1 0.0 0.5 0.0 0.0 0.0 0.0 0.1 1.0 1.0 1.0 1.0 0.1 0.0 0.0 1.0 1.0 0.1 0.0 0.1 0.0 0.1 1.0 0.0 0.0

1.0

1.0 0.0 1.0 0.0 0.1 0.3

1.0

0.5 0.3 1.0 0.0

0.0

1.0 0.5 0.5 1.0 1.0 1.0 1.0 0.1 1.0 0.3 0.5 0.0 0.0 0.0 0.1 0.5 1.0 0.0 0.0

0.1 0.3 0.5

1.0

1.0 1.0 0.5

1.0 0.3 1.0 0.0 1.0 0.5 0.1 0.3 0.5 0.0 1.0 1.0 0.1 0.1 0.0

1.0

0.0 0.0

0.3

0.0 0.1 0.3 0.5 1.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.3 0.1 0.0 1.0 0.0 1.0 1.0 1.0 1.0 0.1 0.1 0.0 1.0 1.0 0.1 0.5 0.5 1.0 0.3 0.0 1.0 0.1 0.0 0.0 0.3 0.1 0.1 0.3 0.0 0.0 0.1 1.0 1.0 0.0 0.5 1.0 0.5 1.0 0.3 1.0 0.0 0.0 1.0 0.5 0.5 1.0 1.0 0.1 1.0 0.5 0.0 0.0 0.0 0.0 0.1 0.0 0.0 1.0 1.0 0.0 0.3 0.0 0.1 0.3 1.0 0.5 0.0 0.1 0.0 0.0 0.1 1.0 1.0 0.1 0.1 0.0 0.0 0.1 0.1 0.0 1.0 1.0 0.5 1.0 0.5 1.0 0.5 0.3 0.1 1.0 0.0 0.3 0.0 1.0 0.0 1.0 0.0 0.5 1.0 0.0 0.0 0.5 1.0 1.0 0.1 0.0 0.0 1.0 1.0 0.0 0.1 0.5 0.0 0.0 0.3 0.0 0.1 0.3 0.1 0.0 1.0 1.0 1.0 1.0 0.0 1.0 1.0 0.0 0.1 0.0 0.5 0.5 1.0 1.0 1.0 1.0 0.1 0.1 1.0 1.0 1.0 1.0 1.0 1.0 0.0 0.5 0.0 0.0 0.0 1.0 1.0 0.1 0.0 0.0 1.0 0.5 0.1 1.0 0.0 1.0 0.3 1.0 1.0 1.0 0.0 0.1 0.3 1.0 0.5 1.0 1.0 0.0 0.1 0.0 0.1 0.0 1.0 0.0 1.0 1.0 1.0 0.0 0.0 0.0 0.0 1.0 0.1 0.0 0.5 1.0 0.5 0.0 0.1 0.3 1.0 0.5 0.3 1.0 0.0 0.5 0.1 0.3 0.5 0.1 1.0 0.0 0.5 1.0 1.0 0.0 0.0 0.0 0.0 0.0 0.0 0.3 0.1 1.0 1.0 1.0 1.0 0.1 0.1 0.5 1.0 0.0 0.1 1.0 0.1 0.3 1.0 0.1 0.0 0.0 0.0 1.0 1.0 0.5 0.0 1.0 0.0 0.0 0.0 0.0 0.0 0.3 0.1 1.0 0.5 1.0 0.1 1.0 1.0 0.1 0.0 0.0 1.0 0.5 0.0 0.5 1.0 0.5 0.0 0.0 0.1 0.0 1.0 1.0 0.0 0.0 0.1 1.0 1.0 0.5 0.0 1.0 0.1 0.1 0.0 1.0 0.5 1.0 0.5 0.0 0.0 0.3 0.3 0.3

Global trust (P2P)

Single trust value per peer Scalable Many malicious peers

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

SLIDE 15

. . Reputation systems

Community trust

0.3 0.1 1.0 0.3 0.0 0.1 0.3 0.5 1.0 0.5 1.0 1.0 0.1 0.1 0.1 0.1 1.0 1.0 1.0 1.0 1.0 0.0 0.0 0.3 0.3 0.5 0.5 0.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.1 1.0 1.0 1.0 1.0 1.0 0.5 1.0 1.0 1.0 1.0 1.0 1.0 0.1 0.0 0.3 0.0

Community trust (F2F)

Separate trust values are computed by each peer Not scalable More trusted peers Fewer peers and resources Can get stuck in local maximum

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

SLIDE 16

. . Simulator

Implementation

Network

Message handler

DHT

Network interface Message handler Distributed search Message handler Transaction manager Message handler Global trust Message handler

Community trust

Peer behavior

Peer behavior Block distributor Feedback listener

Update loop

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A Simulation-based Evaluation of a Hybrid Storage System

SLIDE 17

. . Simulator

Peer types

Honest peer

Always fulfill transactions Give honest ratings

Malicious peer

Always fulfill transactions with malicious peers Otherwise return “corrupt” data with probability pm Always gives positive ratings to malicious peers Otherwise give false (negative) ratings

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

SLIDE 18

. . Simulator

Network

Distribution policies

Global : Only use global (P2P) peers Community : Only use community (F2F) peers Mixed : Use both global (P2P) and community (F2F) peers

File types

0.0 : Trust ≥ 0.0 0.3 : Trust ≥ 0.3 0.6 : Trust ≥ 0.6 0.9 : Trust ≥ 0.9

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A Simulation-based Evaluation of a Hybrid Storage System

SLIDE 19

. . Results

Malicious rate × Average global trust

0.0

0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0

Malicious rate Global trust

Peer types

Honest

Malicious

Global trust (global) Honest: 20 Malicious: 80 Resources: 100 Community size: 20

Malicious Honest

Ideal would be: Thonest ≈ 1 and Tmalicious ≈ malicious rate Global trust is close to the ideal value for both honest and malicious peers

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

SLIDE 20

. . Results

Malicious rate × Block recovery rate

0.0

0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0

Malicious rate Block recovery rate

Policy No−trust Mixed Global Community File types

0.0

0.3 0.6 0.9

Block recovery rate Honest: 20 Malicious: 80 Resources: 100 Community size: 20

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A Simulation-based Evaluation of a Hybrid Storage System

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. . Results

Malicious rate × Block recovery rate (Global peers)

0.0

0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0

Malicious rate Block recovery rate

File types

0.0

0.3 0.6 0.9

Block recovery rate (global) Honest: 20 Malicious: 80 Resources: 100 Community size: 20

t≥0.0 t≥0.3 t≥0.6 t≥0.9

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

SLIDE 22

. . Results

Malicious rate × Block recovery rate (Global peers)

0.0

0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0

Malicious rate Block recovery rate

File types

0.0

0.3 0.6 0.9

Block recovery rate (global) Honest: 20 Malicious: 80 Resources: 100 Community size: 20 1 - 0.0

t≥0.0

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

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. . Results

Malicious rate × Block recovery rate (Global peers)

0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0

Malicious rate Block recovery rate

File types

0.0

0.3 0.6 0.9

Block recovery rate (global) Honest: 20 Malicious: 80 Resources: 100 Community size: 20 1 - 0.9 1 - 0.3

t≥0.3

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

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. . Results

Malicious rate × Block recovery rate (Global peers)

0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0

Malicious rate Block recovery rate

File types

0.0

0.3 0.6 0.9

Block recovery rate (global) Honest: 20 Malicious: 80 Resources: 100 Community size: 20 1 - 0.6

t≥0.6

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

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. . Results

Malicious rate × Block recovery rate (Global peers)

0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0

Malicious rate Block recovery rate

File types

0.0

0.3 0.6 0.9

Block recovery rate (global) Honest: 20 Malicious: 80 Resources: 100 Community size: 20 1 - 0.9

t≥0.9

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

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. . Results

Malicious rate × Block recovery rate (Trust ≥ 0.0)

Mixed > Community > Global

0.0

0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0

Malicious rate Block recovery rate

Policy No−trust Mixed Global Community File types

0.0

Block recovery rate Honest: 20 Malicious: 80 Resources: 100 Community size: 20

Mixed Community Global

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A Simulation-based Evaluation of a Hybrid Storage System

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. . Results

Malicious rate × Block recovery rate (Trust ≥ 0.3)

Mixed > Community > Global

0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0

Malicious rate Block recovery rate

Policy No−trust Mixed Global Community File types

0.0

0.3 0.6 0.9

Block recovery rate Honest: 20 Malicious: 80 Resources: 100 Community size: 20

Mixed Community Global

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A Simulation-based Evaluation of a Hybrid Storage System

SLIDE 28

. . Results

Malicious rate × Block recovery rate (Trust ≥ 0.9)

Mixed > Global > Community

0.0 2.5 5.0 7.5 10.0 0.0 0.2 0.4 0.6 0.8 1.0

Malicious rate Recovered blocks

Policy No−trust Mixed Global Community File types

0.0

0.3 0.6 0.9

Recovered blocks Honest: 10 Malicious: 90 Resources: 100 Community size: 20

Mixed Community Global

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A Simulation-based Evaluation of a Hybrid Storage System

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. . Results

Global trust (P2P) performs better when you need a large number of peers. It is possible to compensate for low trust, and it will perform well as long as the user has chosen appropriate trust requirements. Community trust (F2F) performs better when there are enough peers and resources available in the community graph. It requires much less care when choosing trust requirements, but can easily fail if there are not enough peers available. A combination of global (P2P) and community (F2F) trust performs at least as well as the best of the two, and often better.

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

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. . Conclusions

A hybrid system could work, but some improvements must first be made. Both the P2P and F2F part of the system performs better than expected. Combining P2P and F2F gives the best performance. But using a reputation system may be the most important part.

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System

SLIDE 31

. . Possible improvements

. Create a better model of peer availability and storage costs . . Without a better model of availability or storage cost, and a distribution algorithm that can use it, there is no point in simulating cloud storage. . Find a better trust model . . EigenTrust has limitations that could make it a bad choice for this task. . Generalize . . This kind of system should be able to handle any task that can be described as a transaction. It should be possible to use this to create a platform for trading/sharing other types of resources and use it for, among other things, distributed computing.

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A Simulation-based Evaluation of a Hybrid Storage System

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. . That’s all

Questions?

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A Simulation-based Evaluation of a Hybrid Storage System

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. . Additional details

DHT

1011 11 1100 12 1101 13 1010 10 1001 9 1110 14 1000 8 0111 7 0110 6 0101 5 0100 4 0011 3 0010 2 0001 1 0000 1111 15

1100 12

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A Simulation-based Evaluation of a Hybrid Storage System

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. . Additional details

Distributed search

1 1

0.5

0.375 0.625

0.25 0.75

0.5

0.125 0.25

X Y

X:0.0-0.25 Y:0.3-0.7

Query

Result

000100 000101 000110 000111 010000 010001 010010 010011

1

1 1 1 1

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A Simulation-based Evaluation of a Hybrid Storage System

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. . Additional details

Distributed search

1011 11 1100 12 1101 13 1010 10 1001 9 1110 14 1000 8 0111 7 0110 6 0101 5 0100 4 0011 3 0010 2 0001 1 0000 1111 15

Search space Chord ring

Y

1 1

X

1010 10 1000 8 0010 2 0100 4 1110 14 1001 9 0011 3 0000 1111 15 1100 12 0110 6 0001 1 1011 11 1101 13 0111 7 0101 5

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A Simulation-based Evaluation of a Hybrid Storage System

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. . Additional details

Block distributor

Global peers Community peers Block distributor File Encoder Cloud storage Reserved global Reserved community Reserved cloud

A. Skoglund

A Simulation-based Evaluation of a Hybrid Storage System