Patent ID: 7111189
Filing Date: 2006-09-19
Classification: G06F

Abstract:
1. A method for logging data written by a host computer to a local data storage system at a first site including a local array of data storage devices, comprising: providing a first array controller and a second array controller coupled to each other and also coupled between the host computer and the array; storing, on a log unit in primary cache memory in the first array controller, the data and associated command for every write transaction that occurs between the host computer and the local array; mirroring the primary cache in backup cache memory in the second array controller at the first site; sending the data to a remote storage system located at a second site and linked by at least one link to the local data storage system to create a remote copy; and in the situation wherein the remote copy has not successfully completed and the first array controller has failed, re-playing the data on the log unit by performing: