Asymmetrical striping of mirrored storage device arrays and concurrent access to even tracks in the first array and odd tracks in the second array to improve data access performance

摘要

Mirrored data is contained in a first data storage device array and also in a second data storage device array. However, devices in the first array are not simply mirrors of devices in the second array. Instead, each data storage device in the second array contains a respective share of the mirrored data contained in each data storage device in the first array, and each data storage device in the first array contains a respective share of the mirrored data contained in each data storage device in the second array. Therefore, when a data storage device in one array fails, the failure load is spread over the data storage devices of the other array. For disk storage devices, the mirrored data can be arranged in the first and second arrays so that the mirrored data is contained at the same disk track radius in both arrays in order to equalize seek time for write access or sequential read access to both arrays. Alternatively, the mirrored data can be arranged so that mirrored data at the minimum and maximum track radius in one array is contained at the mean track radius of the other array in order to minimize seek time for random read access.