Allocation of sparing resources in a magnetoresistive solid-state storage device

A method for allocating sparing resources in a magnetoresistive solid-state storage device having magnetoresistive storage cells arranged in rows in a plurality of arrays, comprising the steps of:

• counting a number of failed rows within each array, and counting a number of failed rows within each of a plurality of cross-array row sets comprising one or more rows from each of a subset of the plurality of arrays;
• selecting a cross-array row set having a highest number of failed rows;
• and
• allocating a spare row or rows in an array within the selected cross-array row set having a lowest number of failed rows.

A method for allocating sparing resources in a magnetoresistive solid-state storage device, comprising the steps of:

• providing magnetoresistive storage cells arranged in rows in a plurality of arrays, each array having one or more spare rows capable of replacing a row of that array;
• determining storage cells or groups of storage cells affected by physical failures;
• for each of the plurality of arrays, counting a number of failed rows in that array, where each failed row requires replacement by a spare row;
• allocating spare rows in each array, where the number of failed rows is less than or equal to the number of available spare rows;
• counting a number of failed rows containing cells affected by physical failures in a plurality of cross-array row sets each comprising one or more rows in more than one array;
• selecting active arrays and active cross-array row sets, amongst which it is desired to allocate an available spare row;
• selecting a cross-array row set most affected by physical failures, with reference to the count for each active cross-array row set;
• amongst the arrays contributing rows to the selected cross-array row set, selecting an array having least competition for the spare row, with reference to the count for each array;
• and
• allocating a spare row in the selected array to replace a row contributing to the selected cross-array row set.

A method for allocating sparing resources in a magnetoresistive solid-state storage device having magnetoresistive storage cells arranged in a plurality of arrays, comprising the steps of:

• allocating available sparing resources within each of the plurality of arrays;
• testing the plurality of arrays to identify sets of the storage cells which are not suitable for storing error correction encoded data according to a predetermined error correction coding scheme and a predetermined data storage layout;
• and
• making redundant the identified not suitable sets of cells.

A magnetoresistive solid-state storage device, comprising:

• a plurality of magnetoresistive storage cells arranged in rows in a plurality of arrays, each array having access to one or more spare rows for replacing a row of storage cells in that array;
• a plurality of cross-array row sets comprising one or more rows from each of a subset of the plurality of arrays;
• a test unit arranged to identify storage cells or groups of storage cells affected by physical failures;
• a counting unit arranged to count a number of failed rows within each array, and to count a number of failed rows within each cross-array row set;
• a selecting unit arranged to select one cross-array row set having a highest number of failed rows, and arranged to select one array contributing rows to that cross-array row set having a lowest number of failed rows;
• and
• a sparing allocation unit arranged to allocate a spare row or rows to replace a row or rows of cells of the selected cross-array row set in the selected array.