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Concurrent switch to shadowed device for storage controller and device errors

  • US 5,870,537 A
  • Filed: 03/13/1996
  • Issued: 02/09/1999
  • Est. Priority Date: 03/13/1996
  • Status: Expired due to Term
First Claim
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1. In a data processing system providing remote data shadowing for disaster recovery purposes, said data processing system including a primary site and a secondary site, said primary site having a primary host processor running applications generating I/O operations and record updates, a primary data storage device for receiving said I/O operations and storing said record updates, and a primary storage controller coupled between said primary host processor and said primary data storage device for directing said I/O operations and said record updates to said primary data storage device, said data processing system further including a secondary site having a secondary host processor communicating with said primary host processor, a secondary data storage device for storing a copy of said record updates for data shadowing of said primary data storage device, and a secondary storage controller coupled between said secondary host processor and said secondary data storage device, said secondary storage controller further coupled to said primary host processor, a method in said primary site for switching said secondary data storage device for said primary data storage device to receive said I/O operations and said record updates from said primary host processor comprising steps of:

  • (a) quiescing said I/O operations and said record updates generated by said applications running in said primary host processor and to be received by said primary data storage device;

    (b) verifying that said primary data storage device and said secondary data storage device are a remote copy duplex pair;

    (c) terminating said remote copy duplex pair;

    (d) establishing an opposite direction remote copy duplex pair such that said secondary data storage device serves as a primary device of said remote copy duplex pair and said primary data storage device serves as a shadowing device of said remote copy duplex pair;

    (e) updating said applications running in said primary host processor with a device address of said secondary data storage device substituted as a device address of said primary data storage device; and

    (f) resuming said remote data shadowing using said opposite direction remote copy duplex pair such that subsequent record updates generated by said applications running in said primary host processor are directed through said secondary storage controller, stored in said secondary data storage device, and copied to said primary data storage device.

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