3,932 research outputs found
Analysis of Trade-offs in Fault-Tolerant Distributed Computing and Replicated Databases
This paper examines fundamental trade-offs in fault-tolerant distributed systems and replicated databases built over the Internet. We discuss interplays between consistency, availability, and latency which are in the very nature of globally distributed computer systems and also analyse their interconnection with durability and energy efficiency. In this paper we put forward an idea that consistency, availability, latency, durability and other properties need to be viewed as more continuous than binary in contrast to the well-known CAP/PACELC theorems. We compare different consistency models and highlight the role of the application timeout, replication factor and other settings that essentially determine the interplay between above properties. Our findings may be of interest to software engineers and system architects who develop Internet-scale distributed computer systems and cloud solutions
Storage Solutions for Big Data Systems: A Qualitative Study and Comparison
Big data systems development is full of challenges in view of the variety of
application areas and domains that this technology promises to serve.
Typically, fundamental design decisions involved in big data systems design
include choosing appropriate storage and computing infrastructures. In this age
of heterogeneous systems that integrate different technologies for optimized
solution to a specific real world problem, big data system are not an exception
to any such rule. As far as the storage aspect of any big data system is
concerned, the primary facet in this regard is a storage infrastructure and
NoSQL seems to be the right technology that fulfills its requirements. However,
every big data application has variable data characteristics and thus, the
corresponding data fits into a different data model. This paper presents
feature and use case analysis and comparison of the four main data models
namely document oriented, key value, graph and wide column. Moreover, a feature
analysis of 80 NoSQL solutions has been provided, elaborating on the criteria
and points that a developer must consider while making a possible choice.
Typically, big data storage needs to communicate with the execution engine and
other processing and visualization technologies to create a comprehensive
solution. This brings forth second facet of big data storage, big data file
formats, into picture. The second half of the research paper compares the
advantages, shortcomings and possible use cases of available big data file
formats for Hadoop, which is the foundation for most big data computing
technologies. Decentralized storage and blockchain are seen as the next
generation of big data storage and its challenges and future prospects have
also been discussed
The Raincore Distributed Session Service for Networking Elements
Motivated by the explosive growth of the Internet, we study efficient and fault-tolerant distributed session layer
protocols for networking elements. These protocols are
designed to enable a network cluster to share the state
information necessary for balancing network traffic and
computation load among a group of networking elements.
In addition, in the presence of failures, they allow
network traffic to fail-over from failed networking
elements to healthy ones. To maximize the overall
network throughput of the networking cluster, we assume a unicast communication medium for these protocols. The Raincore Distributed Session Service is based on a fault-tolerant token protocol, and provides group membership, reliable multicast and mutual exclusion services in a networking environment. We show that this service provides atomic reliable multicast with consistent ordering. We also show that Raincore token protocol consumes less overhead than a broadcast-based protocol in this environment in terms of CPU task-switching. The Raincore technology was transferred to Rainfinity, a startup company that is focusing on software for Internet reliability and performance. Rainwall, Rainfinity’s first product, was developed using the Raincore Distributed Session Service. We present initial performance results of the Rainwall product that validates our design assumptions and goals
A Byzantine Fault-Tolerant Ordering Service for the Hyperledger Fabric Blockchain Platform
Hyperledger Fabric (HLF) is a flexible permissioned blockchain platform
designed for business applications beyond the basic digital coin addressed by
Bitcoin and other existing networks. A key property of HLF is its
extensibility, and in particular the support for multiple ordering services for
building the blockchain. Nonetheless, the version 1.0 was launched in early
2017 without an implementation of a Byzantine fault-tolerant (BFT) ordering
service. To overcome this limitation, we designed, implemented, and evaluated a
BFT ordering service for HLF on top of the BFT-SMaRt state machine
replication/consensus library, implementing also optimizations for wide-area
deployment. Our results show that HLF with our ordering service can achieve up
to ten thousand transactions per second and write a transaction irrevocably in
the blockchain in half a second, even with peers spread in different
continents
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