VMSpreader: Multi-tier application resiliency through virtual machine striping

With the growing use of virtual servers for hosting applications, management of large IT infrastructure faces new challenges. In order to reduce the capital expenditure at data centers, virtual server consolidation approaches has been the focus of attention. However, server consolidation inadvertently introduces a new point of failure, which is the physical resource on which the virtual machines are hosted. A common practice is that for a multi-tier application, different tiers of the application are hosted from a single physical machine. Although this is beneficial in maintaining low cost of ownership when the number of hosted applications is low, with increasing number of hosted applications this leads to a skewed distribution of the applications. We propose that spreading the virtual servers of different applications across the available physical resources can lead to a more resilient design for multi-tier application hosting. We formulate the problem of striping the virtual machines across multiple physical machines as an optimization problem. We propose two MIP based techniques, where the first solution is fast but may be infeasible in many cases, while the other one is better in terms of accuracy but takes more time. The solution is tested on data sets representing typical hosting environments.