Patent ID: 7277997

Claim:
An information handling system for mirroring data, comprising: source data storage configured to store and update data; first intermediate data storage configured to store data, said first intermediate data storage associated with said source data storage; target data storage configured to store data; second intermediate data storage configured to store data, said second intermediate data storage associated with said target data storage; and mirroring control configured to conduct first cyclic incremental flashcopy of said source data storage, the beginning of each said first cyclic incremental flashcopy comprising a consistency point, said first cyclic incremental flashcopy copied to said first intermediate data storage and synchronously mirrored to said second intermediate data storage; and to conduct a second cyclic incremental flashcopy of said second intermediate data storage to said target data storage, said second cyclic incremental flashcopy beginning in response to completion of said first cyclic incremental flashcopy; the beginning of said second cyclic incremental flashcopy comprising commit of said consistency point; wherein said mirroring control additionally comprises a loop representing said commit of said consistency point, initiating another first cyclic incremental flashcopy of said source data storage in response to said commit of said consistency point; wherein said mirroring control additionally is configured to respond to an update write for said source data storage, to determine whether data of said source data storage to be overwritten by said update write is present at said first intermediate data storage and said second intermediate data storage; if so, to allow said update write to be written to said source data storage, and to indicate said update write in a future flashcopy map.