HQ replication
Name
191870242-MIT.pdf
Description
Full printable version
Size
5.94 MB
Format
Adobe PDF
Checksum (MD5)
766e6e733e8eef4ad61d2b10dda254fa
Author(s)
Cowling, James (James Alexander)
Advisor(s)
Barbara H. Liskov.
Alternative Title
Hybrid Quorum replication
Date Issued
2007
Publisher
Massachusetts Institute of Technology
Abstract
There are currently two approaches to providing Byzantine-fault-tolerant state machine replication: an agreement-based approach, e.g., BFT, that uses communication between replicas to agree on a proposed ordering of requests, and a quorum-based approach, such as Q/U, in which clients contact replicas directly to optimistically execute operations. Both approaches have shortcomings: the quadratic message cost of inter-replica communication is unnecessary when there is no contention, and Q/U requires a large number of replicas and performs poorly under contention. This thesis present HQ, a hybrid Byzantine-fault-tolerant state machine replication protocol that overcomes these problems. HQ employs a lightweight quorum-based protocol when there is no contention, but uses BFT to resolve contention when it arises. Furthermore, HQ uses only 3f + 1 replicas to tolerate f faults, providing optimal resilience to node failures. We implemented a prototype of HQ, and we compare its performance to BFT and Q/U analytically and experimentally. Additionally, in this work we use a new implementation of BFT designed to scale as the number of faults increases. Our results show that both HQ and our new implementation of BFT scale as f increases; additionally our hybrid approach of using BFT to handle contention works well.
Description
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.
Includes bibliographical references (p. 106-111).
Subjects
Electrical Engineering and Computer Science.
MIT Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
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