HP StorageWorks XP Remote Web Console Software User Manual
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Basic Behavior When Using Multiple Primary and Secondary Storage Systems
This section explains the basic behavior of Universal Replicator for Mainframe under the following
conditions:
•
There are two primary storage systems and two secondary storage systems.
•
The status of all the Universal Replicator for Mainframe pairs that use journal groups in the
extended consistency group is Duplex. For details on extended consistency groups, see
“Extended Consistency Groups” (page 22)
.
•
The primary host issues write requests to Universal Replicator for Mainframe primary data
volumes.
The following figure illustrates a Universal Replicator for Mainframe operation when the above
conditions are satisfied.
Figure 15 A Universal Replicator for Mainframe Operation When Two Primary Storage Systems
and Two Secondary Storage Systems are Used
The numbers in
indicate the order that the processing is performed, and
correspond to the numbers in this procedure:
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 Universal Replicator for Mainframe 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 the journal data. Also, sequence numbers indicating the
order of writing will be added to the journal data.
4.
The Universal Replicator for Mainframe 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.
5.
Secondary storage system 1 (that is, the supervisor DKC) performs arbitration processing. In
other words, secondary storage system 1 restores the journal data of secondary storage
systems 1 and 2, based on the time stamps and the sequence numbers added to the journal
data, so that consistency with the primary data volume is maintained.
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Preparing for Universal Replicator for Mainframe Operations