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1. (WO2001004754) REMOTE DATA COPY USING A PROSPECTIVE SUSPEND COMMAND

Pub. No.:    WO/2001/004754    International Application No.:    PCT/US2000/040330
Publication Date: Fri Jan 19 00:59:59 CET 2001 International Filing Date: Sat Jul 08 01:59:59 CEST 2000
IPC: G06F 11/20
Applicants: HITACHI DATA SYSTEMS CORPORATION
Inventors: MIKKELSEN, Claus, William
DAVENPORT, William, David
DUTCH, Michael, John
MARTINAGE, Cynthia, Anne
RUEHLE, Richard, Allan
Title: REMOTE DATA COPY USING A PROSPECTIVE SUSPEND COMMAND
Abstract:
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 primary controller stops sending the update information to the secondary controller and begins storing indicators of the updated information in the cache memory. The primary controller may resume remote copy operation in response to a command received from the computer by first entering into a pending mode of operation in which cached indicators are used to identify update information that must be sent to the secondary controller to resynchronize the remote copy. When the information for all cached indicators has been sent, normal remote copy operation may be resumed.