HP StorageWorks XP Remote Web Console Software User Manual
Page 65
Figure 14 Using More than One Primary and Secondary Storage System for Remote Copy
When primary hosts write data to primary data volumes, the hosts add a time stamp to the data.
Secondary storage systems check the time stamps and then restore data to data volumes in
chronological order (older data is restored earlier), so that the data update sequence is maintained.
For details about the time-stamping function, see
“Host I/O Time Stamp” (page 25)
.
The term arbitration processing refers to the maintaining of data update sequence through the
execution of the journal restore function based on time stamps. When there is more than one
secondary storage system, one of the secondary storage systems is used to perform tasks including
arbitration processing on the other secondary storage systems.
•
The term supervisor DKC is used to identify the storage system that performs arbitration
processing.
•
The term subordinate DKCs is used to identify the storage systems that are controlled by the
supervisor DKC and are targets of arbitration processing.
The supervisor DKC performs the following function when controlling the subordinate DKCs:
Compares the time stamps of data received by all the secondary storage systems (including the
local storage system) and then performs arbitration processing.
In the example in
, secondary storage system 1 is the supervisor DKC, and
secondary storage systems 2 and 3 are subordinate DKCs.
To perform arbitration processing, the supervisor DKC must be connected with the subordinate
DKCs. For details on connections between secondary storage systems, see
Secondary Storage Systems” (page 67)
.
Using Multiple Primary and Secondary Storage Systems
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