Abstract: After a first device (e.g., a host node in a shared data clustered system that stores a two-way mirrored volume) in a network creates or modifies a description of a layout for a data volume, the first device transmits separate copies of the data volume layout description to a pair of second devices, respectively, for storage in respective memories thereof. The first device may be a host node, and the pair of second devices may be first and second data storage systems. The first device and the pair of second devices are configured so that I/O transactions are transmitted between the first device and either of the pair of second devices. In other words, the first device is contained in a network layer that is different from the network layer that contains the pair of second devices.