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Chapter 3 Preparing for Universal Replicator z/OS Operations 3-17
Hitachi Universal Replicator for IBM /OS User’s Guide
Primary host
Primary site
Master JNL VOL
Journal obtain
Secondary site
Primary storage system 1
Write data
(with time stamp added)
Master JNL VOL
Master JNL VOL
Primary storage system 3
Secondary
data volume
Restore JNL VOL
Journal restore
according to time stamps
Secondary storage system 1
Restore JNL VOL
Secondary storage system 2
Target
port
External
port
Primary storage system 2
Journal group 1 Journal group 1
Journal group 2 Journal group 2
Restore JNL VOL
Secondary storage system 3
Journal group 3
Target
port
External
port
Journal group 3
Journal copy
Secondary
data volume
Secondary
data volume
Primary
data volume
Primary
data volume
Primary
data volume
Figure 3-5 Using More Than One Primary and Secondary Storage
System for Remote Copy
When primary hosts write data to primary data volumes, the hosts add time
stamp to the data. Secondary storage systems check time stamps and then
restore data to data volumes in chronological order (older data are restored
earlier), so that data update sequence is maintained. For details on the time-
stamping function, see section
Host I/O Time-Stamp.