Patent ID: 8200916

Claim:
A color control node comprising: an interface for communicating with a plurality of primary storage controllers, wherein said plurality of primary storage controllers are operatively coupled with primary storage systems at a primary site; and wherein the plurality of primary storage controllers periodically transmit sets of data writes, known as colors, to secondary storage controllers for writing to secondary storage systems at remote sites; and wherein the primary site operates in a normal operating mode while maintaining a current color and associates all writes with said current color without polling the color control node when maintaining said current color; and wherein the primary site switches to a color polling mode when the current color is to be changed to a new color; wherein the switch to the color polling mode causes a querying of the color control node for every write operation; and wherein the color control node further comprises operational capability for asynchronous updating, said asynchronous updating comprising steps of: responsive to the switch to the color polling mode, issuing a command to instruct the primary storage controllers to poll the color control node for the current color prior to associating each write with said current color; receiving an acknowledgment of receipt of the polling command from all of the primary storage controllers; changing to the new color responsive to the acknowledgment; establishing the new color as the current color; issuing a command to the primary storage controllers indicating the new color as the current color for associating all writes and instructing the primary storage controllers to stop polling the control node for the current color; wherein the primary site then reverts to the normal operating mode, with the primary storage controllers associating all writes with the current color without polling the color control node.