A method for allocating workloads to RAID and non-RAID mode disk pools includes: receiving a workload; estimating a cost for allocating the workload to each disk of disks in a disk pool based on a total amount of logical data written to the each disk using a data-average TCO rate model; determining a disk among the disks in the disk pool that minimizes a total cost of ownership (TCO) by comparing costs estimated for the disks; and allocating the workload to the disk.