Machines, systems and methods for handling a client request in a hierarchical multi-tenant data storage system, the method comprising processing a request in subtasks, wherein a subtask is executed with a minimal set of privileges associated with a specific subtenant; extracting a claimed n-level hierarchy of a tenant and sub-tenant identities from the request; extracting authentication signatures or credentials that correspond to a level in the hierarchy; for a first level in the hierarchy, sending the request to a dedicated subtenant authenticator with privilege to validate credentials for a subtenant at the first level; and receiving a confirmation from the dedicated subtenant authenticator, whether the request is authentic.