IMPROVED REMOTE DATA COPY USING A PROSPECTIVE SUSPEND COMMAND

In a computer system, the controller of one or more primary data recording devices sends update information to the controller of one or more secondary data recording devices to maintain a remote copy of data stored on the primary data recording devices. The primary controller receives a command from a computer that specifies a prospective suspend time after which remote copy operation is to be suspended. After the suspend time passes, the primar y controller stops sending the update information to the secondary controller and begins storing indicators of the updated informatio n in the cache