Patent ID: 8069322

Claim:
A method for storage, comprising: configuring a first logical volume on a first storage system and a second logical volume on a second storage system, and configuring the second logical volume as a mirror of the first logical volume, so that the first and second logical volumes form a single logical mirrored volume; receiving at the second storage system a command submitted by a host to write data to the single logical mirrored volume; transferring the command from the second storage system to the first storage system without writing the data to the second logical volume; on receipt of the command at the first storage system, writing the data to the first logical volume; and subsequent to writing the data to the first logical volume, mirroring the data on the second logical volume, wherein: the second storage system is configured to write to the second logical volume after receiving permission from the first storage system, and the first storage system is configured to write to the second logical volume without receiving permission from the second storage system.