Data writing apparatus, data writing/reading apparatus, data writing method and data writing/reading method

A data writing/reading apparatus for writing data into storage means, comprising:

• an upper-rank unit;
• first storage means where data to be written has a redundancy structure;
• and
• a control unit which writes data in said first storage means in response to a command from said upper-rank unit and includes
• second storage means, and
• logical disk writing/reading means for writing in said second storage means data writing of which at an address in said first storage means is instructed by said upper-rank unit and reporting completion of writing to said upper-rank unit, when a redundancy destruction occurs at said address, and reading from said second storage means data for which a command to read from said address is given from said upper-rank unit when that data exists.

A data writing apparatus for writing data into storage means, comprising:

• an upper-rank unit;
• first storage means including data writing of which is instructed by an upper-rank unit and redundancy data and capable of, if data of a size equal to or smaller than a size of said redundancy data is destroyed, ensuring data writing from remaining data while repairing said data writing of which is instructed, in response to a command from said upper-rank unit;
• a control unit which writes data in said first storage means in response to a command from said upper-rank unit and includes
• second storage means, and
• logical disk writing/reading means for writing in said second storage means data for which a command to write at an address in said first storage means is given from said upper-rank unit and reporting completion of writing to said upper-rank unit, when writing is not possible due to an error during data correction in an area including said address.

A method for writing and reading data into and from storage means where data to be written has a redundancy structure, comprising the steps of:

• J) when a redundancy destruction occurs at an address in said first storage means, writing in said second storage means data writing of which at said address is instructed by an upper-rank unit;
• K) reporting completion of writing to said upper-rank unit;
• and
• L) when there is data reading of which from said address is instructed by said upper-rank unit, reading said data from said second storage means.