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System and method to preserve and recover unwritten data present in data cache of a disk subsystem across power outages

  • US 8,347,041 B2
  • Filed: 01/02/2009
  • Issued: 01/01/2013
  • Est. Priority Date: 01/02/2009
  • Status: Expired due to Fees
First Claim
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1. A method of a controller coupled between a host server and a data store comprising:

  • solely packing blocks of a cache memory of the controller corresponding to a dirty data in an order of a volume number and a logical block address within a volume, the dirty data being data from the host server prior to being written to the data store;

    backing up the packed blocks of the cache memory corresponding to the dirty data in a intermediary backup non-volatile storage device distinct from both the cache memory and the data store and storing packing information in the intermediary backup non-volatile storage device, with storing of the packing information at the cache memory being avoided;

    maintaining, in the packing information, a state of the packed blocks of the cache memory corresponding to the dirty data immediately prior to a power outage during the power outage; and

    sequentially accessing the packed blocks of the cache memory corresponding to the dirty data in the intermediary backup non-volatile storage device based on the packing information to transfer the dirty data to the data store following restoration of power.

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