Failover to backup site in connection with triangular asynchronous replication

Computer software, in a computer readable medium, that handles failure of a primary group at a first data center that is part of plurality of data centers providing triangular asynchronous replication, comprising:

• executable code that creates a data mirroring relationship between at least one storage volume at a second data center having a synchronous backup group that is part of the plurality of data centers and at least one storage volume at a third data center having an asynchronous backup group that is part of the plurality of data centers;
• and
• executable code that causes work to be resumed at the second data center.

A method of modifying a data mirroring relationship between a first volume and a second volume, comprising:

• issuing a command to first one of the volumes to modify the data mirroring relationship without communicating with the second one of the volumes;
• and
• the first one of the volumes being reconfigured according to the command independent of the second volume.