HP XP P9500 Storage User Manual
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When data is sent to the secondary systems, the systems check time stamps, which are added
when data is written by the hosts to the P-VOLs. The secondary systems then restore the data to the
S-VOLs in chronological order (older data are restored earlier). This ensures that the update sequence
is maintained. For details on the time stamping function, see
“Host I/O time stamp ” (page 25)
.
The following does not apply to RAID Manager consistency groups with both Cnt Ac-J and Cnt
Ac-J Z journals:
•
The term “arbitration processing" refers to the maintenance of the 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 them is used to perform tasks, including
arbitration processing, on the other secondary systems. The secondary storage system that
performs arbitration processing is called the “supervisor DKC”. Systems that are controlled
by the supervisor DKC and are targets of arbitration processing are called “subordinate DKCs”.
•
The supervisor DKC compares time stamps of data received by all the secondary systems
(including the local system) and then performs arbitration processing. The supervisor DKC
must be connected with the subordinate DKCs.
Note the following when planning for multiple systems:
•
Remote Web Console is required at the primary and secondary sites.
•
BCM is required on the host at the primary and secondary sites.
If including Cnt Ac-J and Cnt Ac-J Z journals together, RAID Manager is required on the
mainframe host.
•
A remote command device for BCM must be created in the supervisor DKC. For details on
secondary systems connections and remote command devices, see
between multiple secondary systems ” (page 35)
•
Journal data is updated in the secondary system based on the time stamp issued from the
mainframe host (or RAID Manager if including Cnt Ac-J Z and Cnt Ac-J journals) and the
sequence number issued by the host with write requests to the primary system. Time and
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Planning volumes, P9500 systems