Abstract: Performance of a virtual machine system is improved by avoiding and/or eliminating bottlenecks in read and write operations. The system analyzes current virtualized workloads and provides working set estimates for individual VMs, hosts, and clusters. The working set estimate data is then utilized to make specific recommendations for different types of backend storage technologies. After procuring a storage device, the system provides a variety of information to aid in the operation of the system. From this information, the system can detect various scenarios and proactively make recommendations to the user about ways in which to improve storage performance at a host level and at a per-VM level. In some embodiments, these recommendations may be implemented automatically without user involvement.