Write set boundary management in support of asynchronous update of secondary storage

A method maintaining colors and color boundaries across multiple storage controllers, the method comprising:

• configuring a polling storage controller to maintain a current color and associate all writes with said current color without polling a color control node for current color information prior to receiving an instruction to poll;
• configuring said polling storage controller to poll said color control node for said current color information subsequent to receiving said instruction to poll;
• and
• configuring said polling storage controller to establish a new color as said current color and associate all writes with said new-and-now-current color without polling said color control node for said current color information subsequent to receiving an instruction to cease polling.

A color control node operative to:

• a) instruct a polling storage controller to poll said color control node for current color information;
• b) change the current color to a new color;
• and
• c) instruct said polling storage controller to cease polling said color control node for said current color information.

A polling storage controller operative to:

• maintain a current color and associate all writes with said current color without polling a color control node for current color information prior to receiving an instruction to poll;
• poll said color control node for said current color information subsequent to receiving said instruction to poll;
• and
• establish a new color as said current color and associate all writes with said new-and-now-current color without polling said color control node for said current color information subsequent to receiving an instruction to cease polling.

A system for maintaining colors and color boundaries across multiple storage controllers, the system comprising:

• a color control node operative to:
• a) instruct a polling storage controller to poll said color control node for current color information;
• b) change the current color to a new color;
• and
• c) instruct said polling storage controller to cease polling said color control node for said current color information;
• and
• a polling storage controller operative to:
• maintain a current color and associate all writes with said current color without polling said color control node for said current color information prior to receiving an instruction to poll;
• poll said color control node for said current color information subsequent to receiving said instruction to poll;
• and
• establish a new color as said current color and associate all writes with said new-and-now-current color without polling said color control node for said current color information subsequent to receiving an instruction to cease polling.

A method for deploying a redundant storage system, the method comprising:

• installing a color control node at a primary data storage site, said color control node operative to:
• a) instruct a polling storage controller to poll said color control node for current color information;
• b) change the current color to a new color;
• and
• c) instruct said polling storage controller to cease polling said color control node for said current color information;
• and
• installing a polling storage controller at said primary data storage site, said polling storage controller operative to:
• maintain a current color and associate all writes with said current color without polling said color control node for said current color information prior to receiving an instruction to poll;
• poll said color control node for said current color information subsequent to receiving said instruction to poll;
• and
• establish a new color as said current color and associate all writes with said new-and-now-current color without polling said color control node for said current color information subsequent to receiving an instruction to cease polling.

A computer program embodied on a computer-readable medium, the computer program comprising:

• a first code segment operative to instruct a polling storage controller to poll a color control node for current color information;
• a second code segment operative to change the current color to a new color;
• and
• a third code segment operative to instruct said polling storage controller to cease polling said color control node for said current color information.

A computer program embodied on a computer-readable medium, the computer program comprising:

• a first code segment operative to maintain a current color and associate all writes with said current color without polling a color control node for said current color information prior to receiving an instruction to poll;
• a second code segment operative to poll said color control node for said current color information subsequent to receiving said instruction to poll;
• and
• a third code segment operative to establish a new color as said current color and associate all writes with said new-and-now-current color without polling said color control node for said current color information subsequent to receiving an instruction to cease polling.