Using a heartbeat signal to maintain data consistency for writes to source storage copied to target storage

A method processed by a computer system, comprising:

• maintaining information on multiple source storage and target storage pairs maintained by control units, wherein the control unit, maintaining the storage pairs, copies writes to the source storage to the target storage;
• managing data consistency across multiple source storage and target storage pairs maintained by the control units
• determining freeze timeouts used by control units maintaining the source and target pairs, wherein in response to a freeze operation with respect to one source and target pair managed by one control unit, the control unit blocks writes to the source storage, wherein the control unit initiates a thaw operation to continue receiving write operations at the source storage after a lapse of the freeze timeout for the source and target pair in response to the freeze operation, and wherein after the thaw operation, received writes completed at the source storage are not transferred to the target storage;
• determining a send signal interval based on the determined freeze timeouts;
• and
• communicating a signal at the send signal interval to the control units maintaining the source and target pairs.

A system in communication with a source storage, target storage, and an application, comprising:

• a plurality of control units;
• a consistency manager managing data consistency across multiple source storage and target storage pairs maintained by the control units;
• a copy relationship associating the source storage and the target storage pairs for control units, wherein writes received at the source storage are transferred by the control unit to the target storage;
• wherein the control units communicate with the consistency manager and each perform operations, the operations comprising:
• determining whether a signal has been received from the consistency manager within a receive signal interval;
• initiating a freeze operation to cease receiving writes at the source storage from the application in response to determining that the signal has not been received within the receive signal interval;
• and
• initiating a thaw operation to continue receiving writes submitted by the application at the source storage without transferring the writes from the application to the target storage after a lapse of a freeze timeout following the freeze operation to maintain data consistency at the target storages of the source and target storage pairs.

An article of manufacture including code executed in a system in communication with a consistency manager, a source storage, a target storage, and an application, wherein the code is executed to perform operations, the operations comprising:

• maintaining a copy relationship associating the source storage and the target storage pair, wherein writes received at the source storage are transferred to the target storage;
• determining whether a signal has been received from the consistency manager managing data consistency across multiple source storage and target storage pairs maintained by different control units within a receive signal interval;
• initiating a freeze operation to cease receiving writes at the source storage from the application in response to determining that the signal has not been received within the receive signal interval;
• and
• initiating a thaw operation to continue receiving at the source storage without transferring the writes from the application to the target storage after a lapse of a freeze timeout following the freeze operation to maintain data consistency at the target storages of the source and target storage pairs.

An article of manufacture including code executed in a system in communication with a plurality of control units, source storages, target storages, and an application, wherein the code is executed to perform operations, the operations comprising:

• maintaining information on multiple source storage and target storage pairs maintained by the control units, wherein the control units maintaining the pairs copy writes to the source storage to the target storage;
• managing data consistency across multiple source storage and target storage pairs maintained by the control units;
• determining freeze timeouts used by the control units maintaining the source and target pairs, wherein in response to a freeze operation with respect to one source and target pair managed by one control unit, wherein the control unit blocks writes to the source storage, wherein the control unit initiates a thaw operation to continue receiving write operations at the source storage after a lapse of the freeze timeout for the source and target pair in response to the freeze operation, and wherein after the thaw operation, received writes completed at the source storage are not transferred to the target storage;
• determining a send signal interval based on the determined freeze timeouts;
• and
• communicating a signal at the send signal interval to the control units maintaining the source and target pairs.