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Method and apparatus for suspending multiple duplex pairs during back up processing to insure storage devices remain synchronized in a sequence consistent order

  • US 5,692,155 A
  • Filed: 04/19/1995
  • Issued: 11/25/1997
  • Est. Priority Date: 04/19/1995
  • Status: Expired due to Fees
First Claim
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1. In a data storage system capable of writing records and record updates and copying said records and record updates for backup purposes, said data storage system including a host processor running an application generating records and record updates, a first duplex pair having a primary data storage device and a secondary data storage device, a second duplex pair having a primary data storage device and a secondary data storage device, a storage controller coupled between said host processor and said first and said second duplex pairs, a method for suspending said first and said second duplex pairs while copying said records and record updates such that said secondary data storage devices of said first and said second duplex pairs remain synchronized in a sequence consistent order comprising steps of:

  • quiescing said first duplex pair by said storage controller in response to an initial quiesce command from said application to inhibit writing future records and record updates from said application to said primary data storage device of said first duplex pair, wherein said quiescing does not halt said application running in said host processor;

    quiescing said second duplex pair by said storage controller in response to a subsequent quiesce command from said application to Inhibit writing future records and record updates from said application to said primary data storage device of said second duplex pair and to synchronize records and record updates copied to said secondary data storage device of said first and second duplex pairs in a sequence consistent order, wherein said quiescing does not halt said application running in said host processor;

    suspending said first and second duplex pairs by said storage controller receiving a suspend command from said application to inhibit copying, by said storage controller to said secondary data storage device of said first and second duplex pairs, of records and record updates transmitted from said application to said primary data storage device of said first and second duplex pairs; and

    signalling said application by said storage controller that said first and second duplex pairs are suspended and subsequent records and record updates can be written to said primary data storage device of said first and second duplex pairs without copying said record to said secondary data storage device of said first and second duplex pairs.

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