Note: The primary storage system does not remove the target journal data from its master journal volume until it receives the sequence numbers of restored journal which is give to the read journal command from the secondary storage system. This is true even if the primary storage system and secondary storage system are connected via a channel extender product.
Selecting and Restoring Journal at the Secondary Storage System
The secondary storage system selects journal data to be promoted to formal data (or " restored") as follows:
1.The secondary storage system gives the number as the management information to distinguish the journal data arrival to the sequence number that is assigned to the journal data from the primary storage system. If the number is 1, the journal data arrived at the secondary storage system. If the number is 0, the journal data has not arrived yet. The secondary storage system determines whether the journal data should be settled or not according to this number. If the journal data has not arrived yet, the secondary storage system waits for the journal data.
2.When the top of queue in the journal group indicates the journal data arrival, the secondary storage system selects the journal data which has the lowest sequence number, and then settles this journal data.
3.The secondary storage system repeats steps (1) and (2) to select and settle the journal data.
Chapter 3 Preparing for Universal Replicator z/OS Operations |
