A dispersed storage (DS) processing unit and method for quality of service (QoS) management in a dispersed or distributed storage network (DSN) are disclosed. The method includes receiving a request to access a set of encoded data slices from a first user computing device of a plurality of user computing devices of the DSN, where the set of encoded data slices is stored in a set of storage units of the DSN, and where a first storage container of a plurality of storage containers of the DSN includes the set of storage units and supports a first group of logical storage vaults of a plurality of logical storage vaults of the DSN, and the first user computing device is affiliated with a first logical storage vault of the first group of logical storage vaults. The method further includes determining a quality of service (QoS) matrix regarding the request when QoS issues exists. The QoS matrix includes classes for the plurality of user computing devices, the plurality of logical storage vaults, and the plurality of storage containers, and a plurality of performance properties for each class. The method further includes determining QoS levels attributable to the first user computing device, the first logical storage vault, and the first storage container. The method further includes determining processing priority of the request based on the QoS matrix and QoS levels, and executing the request in accordance with the processing priority. The performance properties may include a number of requests per frame, data transfer rate, storage quota and latency guarantee, and a dispersed storage (DS) processing unit of the DSN may determine whether the QoS issue is a container level issue, a vault level issue or a user computing device level issue.