Proceedings of the 3rd USENIX Workshop on Hot Topics in Cloud Computing (HotCloud '11). June 14-15, 2011, Portland, OR. Supersedes Carnegie Mellon University Parallel Data Lab Technical Report CMU-PDL-11-105, March 2011.
Matthew Wachs, Lianghong Xu, Arkady Kanevsky*, Gregory R. Ganger
*VMware
Charging for cloud storage must account for two costs: the cost of the capacity used and the cost of access to that capacity. For the cost of access, current systems focus on the work requested, such as data transferred or I/O operations completed, rather than the exertion (i.e., effort/resources expended) to complete that work. But, the provider's cost is based on the exertion, and the exertion for a given amount of work can vary dramatically based on characteristics of the workload, making current charging models unfair to tenants, provider, or both. This paper argues for exertion-based metrics, such as disk time, for the access cost component of cloud storage billing. It also discusses challenges in supporting fair and predictable exertion accounting, such as significant inter-workload interference effects for storage access, and a performance insulation approach to addressing them.