Techniques for controlling data storage system performance

Described are techniques for controlling performance of a data storage system. As a first part of an interactive dialogue, a policy is selected including one or more I/O classes each representing a logical grouping of I/O requests received at the data storage system. As a second part of the interactive dialogue, performance of said data storage system is monitored for each I/O class included in said policy without enforcing said policy. As a third part of the interactive dialogue, at least one performance goal associated with one of said I/O classes is set. The policy is run as a fourth part of the interactive dialogue causing enforcement of the policy on the data storage system in accordance with the at least one performance goal.