1. A computerized storage system comprising: a plurality of storage arrays, each storage array comprising a controller; a storage virtualizer, to which the plurality of storage arrays are externally attached so that a plurality of storage volumes in the plurality of storage arrays are virtually represented to a host as if the plurality of volumes exist on the storage virtualizer, the storage virtualizer, comprising a storage virtualizer management module; a management client sending a management command to the storage virtualizer; wherein the storage virtualizer management module comprises instructions for: receiving a command from the management client; selecting a storage array from the plurality of storage arrays; and delegating the received management command to the selected storage array for processing; wherein the selected storage array sends a result of the delegated received command directly to the management client; wherein the storage virtualizer management module further comprises instructions that execute a process for sending a notice to the management client that the command sent from the management client has been asynchronously started; and wherein the notice indicates the command has been distributed and performed; and wherein the notice indicates that a plurality of results will be sent back.