Symmetrical data change tracking

A system comprising:

• first maintaining means for maintaining a first volume map for a first set of data, wherein the first volume map tracks changes in the first set of data with respect to a version of a second set of data;
• and
• second maintaining means for maintaining a second volume map for the second set of data, wherein
• the second volume map tracks changes in the second set of data with respect to a version of the first set of data;
• and
• third maintaining means for maintaining a first accumulator map for the first set of data, wherein
• the first accumulator map tracks changes in the first set of data;
• and
• using means for using the first accumulator map to update the first volume map when a copy of the first set of data is made.

A system comprising:

• a first maintaining module to maintain a first volume map for a first set of data, wherein the first volume map tracks changes in the first set of data with respect to a version of a second set of data;
• a second maintaining module to maintain a second volume map for the second set of data, wherein
• the second volume map tracks changes in the second set of data with respect to a version of the first set of data;
• a third maintaining module to maintain a first accumulator map for the first set of data, wherein the first accumulator map tracks changes in the first set of data;
• and
• a using module configured to use the first accumulator map to update the first volume map when a copy of the first set of data is made.

A computer system comprising:

• a processor for executing at least one instruction;
• a memory coupled to the processor, the memory comprising:
• first maintaining instructions to maintain a first volume map for a first set of data, wherein the first volume map tracks changes in the first set of data with respect to a version of a second set of data;
• second maintaining instructions to maintain a second volume map for the second set of data, wherein
• the second volume map tracks changes in the second set of data with respect to a version of the first set of data;
• third maintaining instructions to maintain a first accumulator map for the first set of data, wherein
• the first accumulator map tracks changes in the first set of data;
• and
• using instructions configured to use the first accumulator map to update the first volume map when a copy of the first set of data is made.

A computer program product contained on a computer-readable medium, wherein the computer program product comprises:

• first maintaining instructions to maintain a first volume map for a first set of data, wherein the first volume map tracks changes in the first set of data with respect to a version of a second set of data;
• second maintaining instructions to maintain a second volume map for the second set of data, wherein
• the second volume map tracks changes in the second set of data with respect to a version of the first set of data;
• third maintaining instructions to maintain a first accumulator map for the first set of data, wherein
• the first accumulator map tracks changes in the first set of data;
• and
• using instructions configured to use the first accumulator map to update the first volume map when a copy of the first set of data is made.