Method and apparatus for maintaining consistency of data stored in a group of mirroring devices

摘要

In one embodiment, mirroring communication from a second source storage device to a second target storage device in a data mirroring system is disabled when mirroring communication from a first source storage device to a first target storage device is disabled. In another embodiment, information is stored in a data mirroring system identifying at least one subset of a plurality of mirrored source storage devices for which a consistent representation of data is desired to be maintained on at least one corresponding subset of a plurality of target storage devices. In yet another embodiment, at least one of a plurality of mirrored source storage devices is placed in one of a first state, a second state, and a third state. In response to a source storage system receiving a write requesting command chain detected to a mirrored source storage device in the first state, the command chain is permitted to commit and data written by the command chain is transferred to a corresponding target storage device. In response to the source storage system receiving a write-requesting command chain directed to a mirrored source storage device in the second state, the command chain is prevented from committing. In response to the source storage system receiving a write-requesting command chain directed to a mirrored source storage device in the third state, the command chain is permitted to commit without transferring data written by the command chain to a corresponding target storage device.