Use the CESTPATH command to establish ESCON® or FCP (fibre channel protocol) paths between a primary site (source) logical subsystem and a recovery site (target) logical subsystem, or to establish control paths between a master storage control and storage control subordinates in a Global Mirror session.
Each CESTPATH command can establish up to 8 paths (if the primary site logical subsystem supports
eight paths) from one primary site logical subsystem to a single recovery site logical subsystem.
You can link up to 
16
recovery site logical subsystems to one primary site
logical subsystem. These links require that you issue a separate CESTPATH command for each logical
subsystem.
- PRIM
- SEC
- LINK
Attention: The CESTPATH command is a "replace" command. The paths on the command are treated as a path set. Any subsequent CESTPATH command removes paths previously established and replaces them with the new set of paths. You can use the CESTPATH command to selectively add and remove paths. However, you cannot use this command to replace paths if you are trying to switch from ESCON to FCP or vice versa.
If you are trying to switch all your paths in a LSS to LSS association from ESCON to FCP or vice versa, you can use the following procedure:
- Issue a CGROUP FREEZE command to the primary LSS. This will remove all of the ESCON paths and suspend all the PPRC pairs in the LSS to LSS association.
- Issue a CGROUP RUN command to allow Host application I/O to the primary volumes to resume.
- Issue the CESTPATH command using the applicable required parameters to re-establish the PPRC paths.
- Issue the CESTPAIR command with the MODE(RESYNC) option to re-establish the PPRC pairs.
The order in which links are added or deleted is determined by the subsystem.