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Storage system and control method for storing write data requested by a host computer

  • US 8,667,331 B2
  • Filed: 06/16/2011
  • Issued: 03/04/2014
  • Est. Priority Date: 06/16/2011
  • Status: Expired due to Fees
First Claim
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1. A storage system for storing write data requested by a host computer, comprising:

  • a data storage device which stores the write data requested by the host computer; and

    a first controller and a second controller which control input and output of the data to and from the data storage device,wherein the first controller includes;

    at least one host interface which receives a write request from the host computer;

    a first cache memory which temporarily stores the write data requested by the host computer; and

    a first non-volatile memory to which the data stored in the first cache memory is backed up in a power outage,wherein the second controller includes;

    at least one host interface which receives a write request from the host computer;

    a second cache memory which temporarily stores the write data requested by the host computer; and

    a second non-volatile memory to which the data stored in the second cache memory is backed up in a power outage,wherein the storage system further comprises at least one power storage device which supplies electric power to the first and second cache memories and the first and second non-volatile memories during a power outage, andwherein at least one of the first and second controllers is configured to;

    determine whether an amount of charge of the at least one power storage device is equal to or larger than a predetermined amount of power, which is one of an amount of power necessary to transfer the data stored in the first cache memory to the first non-volatile memory, and an amount of power necessary to transfer the data stored in the second cache memory to the second non-volatile memory after power is restored from a power outage;

    store the write data requested by the host computer in the data storage device, without storing the requested write data in neither the first cache memory nor the second cache memory in a case where the amount of charge of the at least one power storage device is smaller than the predetermined amount of power; and

    store the write data requested by the host computer in at least one of the first and second cache memories, and then store the requested write data in the data storage device in a case where the amount of charge of the at least one power storage device is equal to or larger than the predetermined amount of power;

    wherein the at least one power storage device includes a first power storage device, which supplies electric power to the first cache memory and the first non-volatile memory during a power outage, and a second power storage device, which supplies electric power to the second cache memory and the second non-volatile memory during a power outage, andwherein the at least one of the first and second controllers is configured to;

    determine whether an amount of charge of the first power storage device is equal to or larger than the amount of power necessary to transfer the data stored in the first cache memory to the first non-volatile memory after power is restored from a power outage;

    charge the first power storage device with a current larger than a normal charging current in a case where the amount of charge of the first power storage device is smaller than the amount of power necessary to transfer the data stored in the first cache memory to the first non-volatile memory; and

    store the write data requested by the host computer in the at least one of the first and second cache memories, and then store the requested write data in the data storage device in a case where the amount of charge of the first power storage device is equal to or larger than the amount of power necessary to transfer the data stored in the first cache memory to the first non-volatile memory.

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