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Chapter 3 Preparing for Universal Replicator z/OS Operations 3-19
Hitachi Universal Replicator for IBM /OS User’s Guide
Primary host (can add time stamps)
Master JNL VOL
(3)
Secondary site
Primary storage system 1
Primary data
volume
Master JNL VOL
Primary data
volume
Secondary data
volume
Restore JNL VOL
Secondary storage system 1
Secondary data
volume
Restore JNL VOL
Secondary storage system 2
Target
port
External
port
Primary storage system 2
Primary site
(3)
(1)
(1)
(2)
(2)
(4)
(4)
(5)
(5)
Figure 3-6 A URz Operation When Two Primary Storage Systems and
Two Secondary Storage Systems are Used
The numbers in Figure 3-6 indicate the order that the processing is performed,
and correspond to the numbers in the numbered procedure below:
1. The primary host issues write requests to primary storage systems. Time
stamps are added to the data to be written.
2. The primary storage systems receive the write requests, and then notify
the primary host that primary data volumes are updated.
3. The URz journal obtain function stores data updated in primary data
volumes to master journal volumes as journal data. Time stamp
information added by the primary host will be added to journal data. Also,
sequence numbers indicating the order of writing will be added to journal
data.
4. The URz journal copy function copies journal data from the master journal
volumes to the corresponding restore journal volumes. This journal copy
operation will be performed asynchronously with the journal obtain
operation.