Planning Data Transfer Speed before Reversing Data Volumes
When a failure occurs at a host, one of the failure recovery measures is to reverse the primary data volume and the secondary data volume (i.e., change the copy direction). If you want to reverse the primary data volume and the secondary data volume, usually you must ensure that the data transfer speed is the same before and after you reverse these data volumes. Therefore, when you do planning on master journal volumes and restore journal volumes, you need to apply the same scheme to both master and restore journal volumes.
If you do not want to reverse the primary data volume and the secondary data volume, you will be able to cope with a temporary increase in data transfers and a communication path failure between the primary storage system and the secondary storage system, if the master journal volume satisfies conditions mentioned earlier. Therefore, the data transfer speed and the volume capacity required for restore journal volumes are smaller than those required for master journal volumes. Note that the data transfer speed for journal volumes must exceed the data transfer speed in "normal status".
Contributing Factors for Data Transfer Speed between Storage Systems
The speed of data transfer between the primary storage system and the secondary storage system depends on the following factors:
•The bandwidth of data transfer paths
•The journal transfer speed of the DKC
The data transfer speed between the primary storage system and the secondary storage system must exceed the data transfer speed in "normal status" mentioned in Figure
Chapter 3 Preparing for Universal Replicator z/OS Operations |
