Patent ID: 8307129

Claim:
A method for swapping a peer-to-peer remote copy (PPRC) secondary device definition from a subchannel set other than zero to subchannel set zero, the method comprising: identifying a PPRC primary device having a corresponding PPRC primary device definition and which is configured to be accessed by application input/output (I/O), and a PPRC secondary device having a corresponding PPRC secondary device definition, which is configured not to be accessed by the application I/O, wherein the PPRC primary device definition resides at subchannel set zero and the PPRC secondary device definition resides at a subchannel set other than subchannel set zero; initiating a PPRC device definition substitution operation to substitute the PPRC primary device definition within the subchannel set where the PPRC secondary device definition resides and substitute the PPRC secondary device definition within the subchannel set where the PPRC primary device definition resides; and storing the PPRC primary device definition within the subchannel set where the PPRC secondary device definition resides and storing the PPRC secondary device definition within subchannel set zero, including adding back the PPRC primary device definition to the subchannel set where the PPRC secondary device definition resides via a dynamic activate operation, in which the PPRC secondary device assumes operations of the PPRC primary device so that the application I/O proceeds without interruption and in which the application I/O is driven to the PPRC secondary device definition that currently resides within the subchannel set zero.