Asynchronous PPRC will flag tracks on the primary to be duplicated to the secondary when time permits.
PPRC is also the name IBM calls their implementation of the protocol for their storage hardware.
EMC also provides a similar capability on their VPLEX platforms called "MirrorView".
PPRC can be used to provide very fast data recovery due to failure of the primary site.
In IBM zSeries computers with two direct access storage device (DASD) control units connected through dedicated connections, PPRC is the protocol used to mirror a DASD volume in one control unit (the primary) to a DASD volume in the other control unit (the secondary).