Optimizing Multi-tenant Cloud Resource Pools via Allocation of Reusable Time Slots

Typical pricing models for IaaS cloud providers are slotted, using hour and month as time units for metering and charging resource usage. Such models lead to financial loss as applications may release resources much earlier than the end of the last allocated time slot, leaving the cost paid for the rest of the time unit wasted. This problem can be minimized for multi-tenant environments by managing resources as pools. This scenario is particularly interesting for universities and companies with various departments and SaaS providers with multiple clients. In this paper we introduce a tool that creates and manages resource pools for multi-tenant environments. Its benefit is the reduction of resource waste by reusing already allocated resources available in the pool. We discuss the architecture of this tool and demonstrate its effectiveness, using a seven-month workload trace obtained from a real multi-tenant SaaS financial risk analysis application. From our experiments, such tool reduced resource costs per day by 13 % on average in comparison to direct allocation of cloud provider resources.