1. A method implemented in a non-transitory machine-readable storage medium and processed by one or more processors of a machine configured to perform the method, comprising: defining, on the machine, a Service Level Agreement (SLA) policy for a tenant in a multi-tenant storage cloud environment in terms of performance parameters; acquiring, from the machine, controlling factors that affect resource performance for a storage controller assigned to the tenant, wherein the storage controller logically assembled in the multi-tenant storage cloud environment for the tenant as a tenant storage machine specific to the tenant, and the multi-tenant storage cloud environment servicing multiple other tenants, wherein acquiring further includes deriving an equation for the performance parameters based on the controlling factors and correlating past heuristic data for the storage controller with the performance parameters; and evaluating, from the machine, the equation for the performance parameters using measurements collected for the storage controller and using the past heuristic data for calculating resource requirements and selecting resources and resource configurations of the storage controller that meet or exceed the performance parameters based on the calculated resource requirements.