Triangular asynchronous replication

1. A method for a local storage device to facilitate storing recovery data, the method comprising:

the local storage device receiving writes thereto;

the local storage device accumulating chunks of data corresponding to writes thereto, wherein data written after a first time and before a second time is associated with a first chunk of data and data written after the second time is associated with a second chunk of data different than the first chunk of data;

the local storage device providing the first chunk of data to a remote destination while accumulating writes for the second chunk of data;

following providing the first chunk of data to the remote destination, the local storage device sending a message to the remote destination;

in response to receiving a reply to the message, the local storage device transmitting the second chunk of data to the remote destination;

the local storage device providing synchronous data to a local destination; and

the local storage device providing an indicator to the local destination in connection with receiving the reply from the remote destination.

2. A method, according to claim 1 , wherein the local destination maintains a plurality of maps, wherein each of the maps associates synchronous data being provided thereto with a specific chunk of data.

3. A method, according to claim 2 , wherein, in response to receiving an indicator in connection with creation of a new chunk of data, the local destination points to a new map.

4. A method, according to claim 3 , wherein there are two maps.

5. A method, according to claim 3 , wherein there are more than two maps.

6. A method, according to claim 1 , further comprising:

in response to the local destination failing to acknowledge synchronous data provided thereto, the remote destination maintaining a map of data written thereto.

7. A method, according to claim 6 , further comprising:

in response to the local destination failing to acknowledge synchronous data provided thereto, the remote destination maintaining a count of a number of times a new chunk of data is created.

8. Software, provided in a computer readable storage medium, that causes recovery data to be stored, the software comprising:

executable code that accumulates chunks of data corresponding to writes, wherein data written after a first time and before a second time is associated with a first chunk of data and data written after the second time is associated with a second chunk of data different than the first chunk of data;

executable code that provides chunks of data to a remote destination while accumulating writes for the second chunk of data;

executable code that sends a message to the remote destination following providing the first chunk of data to the remote destination;

executable code that transmits the second chunk of data to the remote destination in response to receiving a reply to the message;

executable code that provides synchronous data to a local destination; and

executable code that provides an indicator to the local destination in connection with receiving the reply from the remote destination.

9. Software, according to claim 8 , wherein the local destination includes executable code that maintains a plurality of maps, wherein each of the maps associates synchronous data being provided thereto with a specific chunk of data.

10. Software, according to claim 9 , wherein, in response to receiving an indicator in connection with creation of a new chunk of data, the local destination points to a new map.

11. Software, according to claim 10 , wherein there are two maps.

12. Software, according to claim 10 , wherein there are more than two maps.

13. Software, according to claim 8 , further comprising:

executable code at the remote destination that, in response to the local destination failing to acknowledge synchronous data provided thereto, maintains a map of data provided thereto.

14. Software, according to claim 13 , further comprising:

executable code at the remote destination that, in response to the local destination failing to acknowledge synchronous data provided thereto, maintains a count of a number of times a new chunk of data is created.

15. A system for storing recovery data, comprising:

a source group that includes a plurality of storage devices, at least one of the storage devices accumulating chunks of data corresponding to writes thereto, wherein data written after a first time and before a second time is associated with a first chunk of data and data written after the second time is associated with a second chunk of data different than the first chunk of data;

a remote destination coupled to the source group to receive therefrom chunks of data, wherein the source group provides the first chunk of data to the remote destination while accumulating writes for the second chunk of data, sends a message to the remote destination following providing the first chunk of data to the remote destination, and, in response to receiving a reply to the message, transmits the second chunk of data to the remote destination; and

a local destination coupled to the source group to receive synchronous data therefrom, wherein the source group provides an indicator to the local destination in connection with receipt of the message from the remote destination.