Patent ID: 6446220
Filing Date: 2002-09-03
Classification: G06F

Abstract:
A method for updating data, comprising the steps of:receiving, with a first processing unit, a data update to a data block in a first storage device, wherein parity data for the data block is maintained in a second storage device, and wherein a parity group is comprised of the data block and the parity data; processing by the first processing unit a first data structure indicating parity groups controlled by a second processing unit and determining, from processing the first data structure, that the second processing unit controls access to the parity group; sending a message, with the first processing unit, to the second processing unit controlling access to the parity group requesting control of access to the parity group after determining that the first processing unit does not control access to the parity group including the data block to update; modifying the first data structure by the first processing unit to indicate that the first processing unit controls access to the parity group after receiving a message from the second processing unit granting control of access to the parity group and wherein the second processing unit modifies a second data structure to indicate that that first processing unit controls access to the parity group to which the second processing unit granted control; determining new parity data from the data update, the data at the data block in the first storage device, and the parity data in the second storage device; and writing the data update to the data block in the first storage device and the new parity data to the second storage device.