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STORAGE DEVICE

  • US 20100180068A1
  • Filed: 07/04/2007
  • Published: 07/15/2010
  • Est. Priority Date: 08/09/2006
  • Status: Active Grant
First Claim
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1. A hard-disk-drive compatible storage device connected to a host for use, the storage device comprising:

  • a semiconductor nonvolatile memory having a file management information section and a data section and configured to save data sent from a host in the data section and save file management information relevant to saving the data in the file management information section;

    a volatile memory;

    a controller for performing control on write and read of data with the host under control of the host; and

    a power supply maintaining unit, whereinthe storage device is configured to be driven with electric power supplied from the host, andthe controller is configured to;

    (1) manage the write and read of the data exchanged with the host by a data management system compatible with a data management system for hard disks;

    (2) read file management information from the file management information section in the nonvolatile memory and write the same in the volatile memory upon startup of the host;

    (3) perform read and write based on the file management information in the volatile memory, and at the same time, update the file management information within the volatile memory when a read operation and a operation from the host to the nonvolatile memory are observed;

    (4) perform allocation of destinations to save the data so that the data is saved in the volatile memory when the data sent from the host matches a condition set in advance with respect to at least either of a data size, a rewriting frequency, or a vacancy ratio by block, and the data is saved in the nonvolatile memory when the data sent from the host does not match the condition set in advance;

    (5) read the updated file management information recorded in the volatile memory and write the same in the nonvolatile memory corresponding to an end operation in the host; and

    (6) switch power supply to the power supply maintaining unit and also performs control on cutting off a signal from the host when unexpected power shutdown occurs on the host side, and read the updated file management information recorded in the volatile memory and write the same in the nonvolatile memory with using electric power supplied from the power supply maintaining unit.

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