Incremental update control for remote copy

A system for asynchronously transmitting one or more incremental database updates from a primary volume at a primary site to a remote volume at a remote site, the primary site and the remote site interconnected by at least one communication link, the system comprising:

• a local controller associated with the primary site comprising:
• a means for destaging modified data to the primary volume for a current database update and updating one or more bits in a first bitmap at the primary site that indicate one or more tracks on the primary volume that are to be overwritten with the modified data;
• a means for transferring the first bitmap to a second bitmap at the primary site for indicating the modified data that is to be transmitted to the remote volume at the remote site for the current database update;
• and
• a means for synchronizing the primary volume at the primary site with the remote volume at the remote site for the current database update by transmitting the modified data to the remote volume as indicated by one or more bits in the second bitmap, wherein the one or more incremental database updates at the primary volume of the primary site are decoupled from transmission of the one or more incremental database updates to the remote volume at the remote site.

A controller associated with a primary site for asynchronously transmitting one or more incremental database updates from a primary volume at the primary site to a remote volume at a remote site, the primary site and the remote site interconnected by at least one communication link, the controller comprising:

• means for destaging modified data to the primary volume for a current database update and updating one or more bits in a first bitmap at the primary site that indicate one or more tracks on the primary volume that are to be overwritten with the modified data;
• means for transferring the first bitmap to a second bitmap at the primary site for indicating the modified data that is to be transmitted to the remote volume at the remote site for the current database update;
• and
• means for synchronizing the primary volume at the primary site with the remote volume at the remote site for the current database update by transmitting the modified data to the remote volume as indicated by one or more bits in the second bitmap, wherein the one or more incremental database updates at the primary volume of the primary site are decoupled from transmission of the one or more incremental database updates to the remote volume at the remote site.

A program storage device, tangibly embodying a program of instructions executable by a machine to perform a method for asynchronously transmitting one or more incremental database updates from a primary volume at a primary site to a remote volume at a remote site, the primary site and the remote site interconnected by at least one communication link, the method comprising the steps of:

• (a) destaging modified data to the primary volume for a current database update and updating one or more bits in a first bitmap at the primary site that indicate one or more tracks on the primary volume that are to be overwritten with the modified data;
• (b) transferring the first bitmap to a second bitmap at the primary site for indicating the modified data that is to be transmitted to the remote volume at the remote site for the current database update;
• and
• (c) synchronizing the primary volume at the primary site with the remote volume at the remote site for the current database update by transmitting the modified data to the remote volume as indicated by one or more bits in the second bitmap, wherein the one or more incremental database updates at the primary volume of the primary site are decoupled from transmission of the one or more incremental database updates to the remote volume at the remote site.