High Availability › Overview › How Synchronous PPRC works

How Synchronous PPRC works

The PPRC synchronous copy functions are:

• A PPRC data copy to the recovery storage subsystem is synchronous with the I/O operation of the primary volume. This means that the primary system writes data to a volume of the primary storage subsystem. The data is then transferred to cache and nonvolatile storage (NVS), and the storage control sends channel end status to the host.
• The primary site storage control then initiates an I/O channel program to the recovery site storage control to transfer the updated data.
• The primary site storage control returns device end status to the primary system when the transfer to the recovery site storage control cache and NVS is complete.
• The primary system notifies the application program that the operation is complete.

Note: The PPRC copy function does not consider the primary system DASD write operation complete until the data that is sent to the recovery storage subsystem has received channel end and device end status from the secondary volume storage control. Each primary system write to the recovery subsystem causes an increase to the primary system response time.

High Availability PPRC features

ISPF Interface

OPSVIEW option 3.6 provides an ISPF user interface which provides the following functions:

• Create, display, and delete PPRC paths connecting primary and secondary ESSs.
• Create, display, and delete PPRC mirrored volumes pairs.
• Save and view the current PPRC environment definitions in a flat file.
• Offers a wizard style of creating the PPRC paths and mirrored volumes.

OPS/REXX Host Environment

The OPS/REXX ADDRESS SOF host environment has been extended with the set of PPRC related commands. These commands let users write OPS/REXX programs to issue PPRC commands directly. Command output is returned in OPS/REXX stem variables for interrogation by the calling program.

Saved PPRC Configuration

You can specify the PPRC definitions by manually editing the text flat file. This file is specified in your SOF/PPRC z/OS starting procedure, or through the OPSVIEW ISPF dialog. This flat file is updated with any changes you made to the PPRC environment through the OPSVIEW interface.