Computer storage drive array with command initiation at respective drives

Abstract

In a data processing system, a redundant array of storage devices is provided for storing data from a host data processing system. When a selected, storage device receives a write command, the selected storage device reads old data from the logical address specified in the write command, and temporarily stores such old data in a buffer. Next, the selected storage device writes new data from the host data processing system to a location specified in the write command. Thereafter, an XOR operation is performed in the selected storage device between the new data and the old data to produce intermediate data. The intermediate data is then transferred to a second storage device within the array. Within the second storage device, old parity data is read from the media in the second storage device and placed in a buffer. Next, an XOR operation is performed in the second storage device between the intermediate data and the old parity data to produce new parity data. Finally, such new parity data is written in the second storage device. Commands for reading data, writing data, performing XOR operations, and transferring data are all generated and executed within the storage devices which comprise the redundant array of storage devices.