Data reconstruction method and system wherein timing of data reconstruction is controlled in accordance with conditions when a failure occurs

A data reconstruction system comprising:

• a plurality of data storage means for storing divided data in parallel, the divided data being data divided into one of bit units, byte units, and arbitrary units;
• at least one error correcting data storage means for storing error correcting data for the divided data;
• at least one spare data storage means for storing reconstructed divided data;
• data reconstructing means for reconstructing divided data stored in any of the plurality of data storage means in which a failure has occurred based on (1) divided data stored in remaining ones of the plurality of data storage means in which a failure has not occurred and (2) the error correcting data stored in the at least one error correcting data storage means, and storing the reconstructed divided data in the at least one spare data storage means;
• monitoring means for monitoring operation of the plurality of data storage means and producing an output when a failure has occurred in any of the plurality of data storage means;
• and
• control means for
• receiving requests for accessing the plurality of data storage means from a host unit,
• setting a data reconstruction frequency at which the data reconstructing means is to reconstruct the divided data,
• determining, for each failure which has occurred, a nature of the failure based on the output of the monitoring means, and
• controlling the data reconstructing means to switch between a first operating mode and a second operating mode in accordance with the data reconstruction frequency and the nature of the failure,
• wherein in the first operating mode, the data reconstructing means reconstructs the divided data, and
• wherein in the second operating mode, the data reconstructing means temporarily stops reconstructing the divided data to allow the host unit to access the plurality of data storage means.

A data reconstruction method comprising the steps of:

• monitoring operation of a plurality of data storage means for storing divided data in parallel and detecting when a failure has occurred in any of the plurality of data storage means, the divided data being data divided into one of bit units, byte units, and arbitrary units;
• determining a total number of the plurality of data storage means in which a failure has occurred;
• setting a data reconstruction frequency at which divided data stored in any of the plurality of data storage means in which a failure has occurred is to be reconstructed;
• if the total number of the plurality of data storage means in which a failure has occurred is less than a first predetermined value, reconstructing the divided data based on (1) divided data stored in remaining ones of the plurality of data storage means in which a failure has not occurred and (2) error correcting data for the divided data stored in at least one error correcting data storage means;
• and
• storing the reconstructed divided data in at least one spare data storage means;
• wherein the reconstructing step includes the steps of
• (1) reconstructing the divided data without stopping, and
• (2) temporarily stopping reconstructing the divided data to allow the plurality of data storage means to be accessed;
• and
• wherein each of the steps (1) and (2) of the reconstructing step is performed based on (1) the total number of the plurality of data storage means in which a failure has occurred and (2) the data reconstruction frequency.

A data reconstruction method comprising the steps of:

• monitoring operation of a plurality of data storage means for storing divided data in parallel and detecting when a failure has occurred in any of the plurality of data storage means, the divided data being data divided into one of bit units, byte units, and arbitrary units;
• if a failure is detected in any of the plurality of data storage means, defining a plurality of first time zones and a plurality of second time zones alternating with the first time zones;
• during each of the first time zones, reconstructing a part of the divided data stored in any of the plurality of data storage means in which a failure has occurred by performing the steps of
• reading divided data stored in remaining ones of the plurality of data storage means in which a failure has not occurred,
• reading error correcting data for the divided data stored in at least one error correcting data storage means,
• reconstructing the part of the divided data based on the divided data read from the remaining ones of the plurality of data storage means in which a failure has not occurred and the error correcting data for the divided data read from the at least one error correcting data storage means, and
• storing the reconstructed part of the divided data in at least one spare data storage means;
• during each of the second time zones, allowing the plurality of data storage means to be accessed by a host unit in response to access requests received from the host unit;
• and
• if an access request received from the host unit is a read request for reading a part of the divided data stored in any of the plurality of data storage means in which a failure has occurred which has not been reconstructed in a first time zone, reconstructing the part of the divided data which has not been reconstructed in a first time zone by performing the steps of
• reading divided data stored in the remaining ones of the plurality of data storage means in which a failure has not occurred,
• reading error correcting data for the divided data stored in the at least one error correcting data storage means,
• reconstructing the part of the divided data which has not been reconstructed in a first time zone based on the divided data read from the remaining ones of the plurality of data storage means in which a failure has not occurred and the error correcting data for the divided data read from the at least one error correcting data storage means, and
• sending the reconstructed part of the divided data which has not been reconstructed in a first time zone to the host unit.