Replication for Dependability on Virtualized Cloud Environments



Execution of critical services traditionally requires multiple distinct replicas, supported by independent network and hardware. To operate properly, these services often depend on the correctness of a fraction of replicas, usually over $2/3$ or $1/2$. Defying the ideal situation, economical reasons may tempt users to replicate critical services onto a single multi-tenant cloud infrastructure. Since this may expose users to correlated failures, we assess the risks for two kinds of majorities: a conventional one, related to the number of replicas, regardless of the machines where they run; and a second one, related to the physical machines where the replicas run. This latter case may exist in multi-tenant virtualized environments only. We evaluate crash-stop and Byzantine faults that may affect virtual machines or physical machines. Contrary to what one might expect, we conclude that replicas do not need to be evenly distributed by a fixed number of physical machines. On the contrary, we found cases where they should be as unbalanced as possible. We try to systematically identify the best defense for each kind of fault and majority to conserve.


Cloud computing, Fault-Tolerance, Dependability, Virtualization


Cloud Computing

Related Project

TRONE: Trustworthy and Resilient Operations in a Network Environment (CMU-PT/RNQ/0015/2009)


The 10th International Workshop on Middleware for Grids, Clouds and e-Science - MGC 2012, December 2012

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Cited by

Year 2014 : 1 citations

 Security for Future Networks (SecFuNet), Heiko Niedermayer and Feitosa, Eduardo and da Silva Fraga, Joni and Malichevskyy, Oleksandr and Barreto, Luciano, 2014.

Year 2013 : 2 citations

 16181355158423902086 Security for Future Networks (SecFuNet) Deliverables/Secfunet_D5_1.pdf HN TUM, E Feitosa, J da Silva Fraga, O Malichevskyy… Publication/NA Year/NA

 Diego Kreutz, Heiko Niedermayer, Eduardo Feitosa, Joni da Silva Fraga, Oleksandr Malichevskyy, "Security for Future Networks", D5.1 - Architecture Components for Resilient Networks, 2013.