OptiSpot: minimizing application deployment cost using spot cloud resources.

Daniel J. Dubois,Giuliano Casale

doi:10.1007/s10586-016-0568-7

Abstract

The spot instance model is a virtual machine pricing scheme in which some resources of cloud providers are offered to the highest bidder. This leads to the formation of a spot price, whose fluctuations can determine customers to be overbid by other users and lose the virtual machine they rented. In this paper we propose OptiSpot, a heuristic to automate application deployment decisions on cloud providers that offer the spot pricing model. In particular, with our approach it is possible to determine: (i) which and how many resources to rent in order to run a cloud application, (ii) how to map the application components to the rented resources, and (iii) what spot price bids to use to minimize the total cost while maintaining an acceptable level of performance. To drive the decision making, our algorithm combines a multi-class queueing network model of the application with a Markov model that describes the stochastic evolution of the spot price and its influence on virtual machine reliability. We show, using a model developed for a real enterprise application and historical traces of the Amazon EC2 spot instance prices, that our heuristic finds low cost solutions that indeed guarantee the required levels of performance. The performance of our heuristic method is compared to that of nonlinear programming and shown to markedly accelerate the finding of low-cost optimal solutions.

Highlights

Cloud computing is a popular paradigm for offering compute capacity as a service
Instead, resources are offered at a variable price, called the spot price, which is arbitrarily decided by the cloud provider
If the bid price is greater than the current spot price, the virtual machine will be charged at the spot price

Summary

Introduction

Cloud computing is a popular paradigm for offering compute capacity as a service. In particular, the cloud gives flexibility to decide and modify the speed, the number, and the lease time of virtual machines (VMs). The advantage of spot instances is that their price tends to be lower than the on-demand price most of the time, but from time to time, when the cloud provider has a shortage of resources, it can temporarily make the spot price steep (much higher than the on-demand price) in order to have most of spot resources back. This makes the decision of choosing a bid price both difficult and important. While a number of works have considered this problem in recent years [9,17,29,31], the problem of deciding bid prices in light of performance requirements or constraints on the application architecture is more complex and still poorly understood

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