Patent ID: 7133986
Filing Date: 2006-11-07
Classification: G06F

Abstract:
1. A method for forming a consistency group, comprising: receiving a first command from a master controller to generate a first data structure to indicate updates to a slave storage unit to form a consistency group initiated by the master controller, wherein data in the slave storage unit in the consistency group is transmitted consistent as of a point-in-time; generating the first data structure in response to the first command; transmitting complete to the master controller after generating the first data structure; copying updated data in the slave storage unit indicated in a second data structure to a remote storage, wherein the data is copied to form the consistency group, wherein updates to the slave storage unit received while copying the updated data indicated in the second data structure to form the consistency group are indicated in the first data structure; and transmitting complete to the master controller after successfully copying the data in the slave storage unit indicated in the second data structure to the remote storage; receiving a second command from the master controller to cause the copying of the slave storage unit data in the remote storage to a remote backup storage after transmitting the complete indicating that the slave storage unit data was successfully copied to the remote storage; and transmitting a third command to a remote controller managing the remote storage to cause the copying of the slave storage unit data in the remote storage to the remote backup storage in response to receiving the third command.