Hybrid Spot Instance based Resource Provisioning Strategy in Dynamic Cloud Environment Naidila Sadashiv Dilip Kumar S M R S Goudar Redknee Bangalore, India 560 045 Email: rsgoudarl@gmail.com Dept. of Computer Sci. and Engg. Dept. of Computer Sci. and Engg. Acharya Institute of Technology Bangalore, India 560 107 Email: sadashiv@acharya.ac.in University Visvesvarya College of Engg. Bangalore, India 560 001 Email: dilipkumarsm@gmail.com Abstrct-Utilization of resources to the maximum extent in large scale distributed cloud environment is a major challenge due to the nature of cloud. Spot Instances in the Amazon Elastic Compute Cloud (EC2) are provisioned based on highest bid with no guarantee of task completion but incurs the overhead of longer task execution time and price. The paper demonstrates the last partial hour and cost overhead that can be avoided by the proposed strategy of Hybrid Spot Instance. It aims to provide reliable service to the ongoing task so as to complete the execution without abruptly interrupting the long running tasks by redefning the bid price. The strategy also considers that on demand resource services can be acquired when spot price crosses on-demand price and thereby availing high reliability. This will overcome the overhead involved during checkpointing, restarting and workload migration as in the existing system, leading to efcient resources usage for both the providers and users. Service providers revenue is carefully optimized by eliminating the free issue of last partial hour which is a taxing factor for the provider. Simulation carried out based on real time price of various instances considering heterogenous applications shows that the number of out-of-bid scenarios can be reduced largely which leads to the increased number of task completion. Checkpointing is also minimized maximally due to which the overhead associated with it is reduced. This resource provisioning strategy aims to provide preference to existing customers and the task which are nearing the execution completion. Index Terms-Cloud Computing; Resource Provisioning; Spot Instances; Bidding; Checkpointing; Reliability; I. INTRODUCTION Cloud computing is an emerging paradigm that has rev olutionized the consumption model of resources. With this paradigm, customers are able to access resources and services on the fy based on a pay-as-you-go model. Resources can also be booked in advance in order to be assured of the availability of desired resources. This is similar to market oriented system where maximizing the proft is the objective. Due to the dynamic nature of cloud computing where in the demand and supply of resource is diffcult to predict, many of the resource are left idle. In order to utilize the idle resources efciently, Spot Instance (SI) is introduced by Amazon [1]. Amazon is the pioneer in the introduction of the Spot Instance. The aim of SI is to generate revenue from the under utilized resources and there by consider the economy aware applications. Users who seek the service make a bid based on the current SI price that is publicly available for diferent 978-1-4799-5958-7/14/$31.00 ©2014 IEEE type of instances. These instances are launched using the highest bid strategy. If the new bidding price is more than the current spot price, then the current user's Spot Instances will be terminated in no time and is termed as out-of-bid. Hence the pricing of these resources are volatile and depends on the supply and demand in the market. In such a dynamic pricing environment which is prone to out-of-bid situation shall involve fault tolerant techniques. Most commonly used fault tolerant techniques are migration, job duplication and checkpointing-based approach. They involve in saving the state of an application or a process during execution and restoring the saved state, for which a large storage capacity and time is required [6], [14], [15], [17]. Fault tolerance is achieved by these approaches but at a very high cost which should be shared by the providers as well as users [3], [16]. Users are attracted to the minimum cost of the resource but end up paying more, and sometimes it exceeds the on-demand price. Varying types of applications like economy aware applications, compute intensive, as well in data analytic scenarios, such as execution of MapReduce tasks [9], [14] and HTC are now aiming to reap the benefts of SI. Hence providers should provide more fexibility such that users are given a chance for their task completion rather than abrupt task termination [11], [19]. Users owe these resources at nominal price but not for free of cost. Our main objective is to efciently utilize the idle resources by avoiding the overhead during checkpointing and out-of bid time. In this paper we propose a Hybrid Spot Instance (HSI) resource provisioning strategy that gives a chance to the existing users to continue with resource usage at out-of bid time by redefning the running task's bid. We also present the overhead that the service provider faces which will be addressed by using the HSI. User's task will be migrated to on-demand scheme when SI price meets the on-demand price. The rest of this paper is organized as follows. In Section II we discuss some of the recent related works and highlight their limitations and drawbacks. In Section III we present the Hybrid Spot Instance algorithm. In Section IV we show the simulation results with discussion and in Section V we present the concluding remarks.