Establishing PPRC FCP connections

There are two differences between establishing a PPRC FCP path versus a PPRC ESCON® path:

You must specify the World Wide Node Name for the primary logical subsystem and the secondary (recovery) logical subsystem instead of a serial number.
You must specify the FCP source and destination adapter numbers in the LINK addresses.

Each ESS has a unique World Wide Node Name (WWNN). The WWNN is displayed on the initial panel of the ESS Specialist. The WWNN is an 8 byte value. The WWNN for the primary logical subsystem is checked to ensure the primary WWNN specified in the CESTPATH TSO command or the PESTPATH ANTRQST API request is valid.

To establish an FCP link between subsystems, the establish path request must supply a WWNN for the primary logical subsystem and a WWNN for the secondary logical subsystem. You cannot specify a WWNN for one logical subsystem and a serial number for the other logical subsystem, this causes the establish path command or request to fail.

When an FCP connection between ESS subsystems is required, the LINK address(es) specify an FCP adapter in the primary logical subsystem, and an FCP adapter in the secondary logical subsystem. The FCP adapters are assigned numbers during ESS configuration. The FCP adapter numbers are two bytes in length. Although the first byte of the FCP adapter number is generally zero, two bytes are needed for future FCP adapter configurations. When the PPRC establish paths command or request parameter checking is successful, the WWNN of the secondary storage subsystem and the FCP adapter number are combined to create the World Wide Port Name (WWPN) address. The WWPN is sent directly to the secondary subsystem (direct point-to-point connection) or is sent to the Fibre Channel fabric switch where the request is routed to the appropriate secondary subsystem. If a secondary subsystem with the requested WWPN is found, the secondary subsystem FCP adapter assigns a port in the adapter to receive PPRC communications from the primary subsystem. Although the FCP adapter port in the secondary subsystem is linked to the primary subsystem, the secondary FCP adapter port can be used for other communications as needed.

When the PPRC link between subsystems is no longer needed, you must issue a CDELPATH TSO command or PDELPATH ANTRQST API request to remove all links between the primary storage subsystem and the secondary storage subsystem. Deleting the paths allows the use of the affected storage adapters (ESCON or FCP) for other communications. Before the you delete all the paths, all PPRC volume pairs must be deleted.

Synchronous PPRC is supported over FCP for distances up to 200 km.

Note: If the paths were established using WWNN for the primary and secondary, the CDELPATH must also specify WWNN for the primary and secondary.

For additional information about using the CESTPATH AND CDELPATH TSO commands, refer to Peer-to-Peer Remote copy command descriptions.

For additional information about using the PESTPATH and PDELPATH ANTRQST API requests, refer to ANTRQST and ANTRQSTL macros – call to the system data mover API.