Method and apparatus for data duplexing in storage unit system

摘要

With the purpose of achieving consistent non-synchronous copying of data from a plurality of primary side control units to a plurality of secondary side control units, all of the secondary side control units are connected via a loop, and each of the secondary side control units determines guarantee time by circulating a time added to the data received from the primary side control units via said loop communication route. A consistent data copying is guaranteed by circulating the determined guarantee time via the loop communication route.