An Online Integrated Resource Allocator for Guaranteed Performance in Data Centers

As bandwidth is shared in a best-effort way in today's data centers, traffic generated between a set of VMs (virtual machines) affect the traffic between another set of VMs (possibly belonging to another tenant) sharing the same physical links, leading to unpredictable performance of applications running on these VMs. This article addresses the problem of allocation of not only server resources (computational and storage) but also network bandwidth, to provide performance guarantees in multi-tenant data centers. Bandwidth being a critical shared-resource, we formulate the problem as an optimization problem that minimizes bandwidth demand between clusters of VMs of a tenant; and we prove it as NP-hard. We develop fast online heuristics as an integrated resource allocator (IRA) that decides on the admission of dynamically arriving requests, and allocates resources for the accepted ones. We also present a modified version of IRA, called B-IRA that bounds the cost of bandwidth allocation, while exploring smaller search space for solution. We demonstrate that, IRA accommodates significantly higher number of requests in comparison to a load-balancing resource allocator (LBRA) that does not consider reducing bandwidth between clusters of VMs. IRA also outperforms B-IRA when traffic demands of VMs in an input are not localized.