HP XP P9500 Storage - Manual (Page 36)

Figure 1 Extender Connection
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Set port topology to the following:
NL/FL port: Fab on, FC-AL ◦
◦ F port: Fab on, Point-to-Point
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Best practice is to create at least two independent data paths (one per cluster) between the
primary and secondary system for hardware redundancy for this critical element.
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When 4,000 pairs or more are used, we recommend that you restrict the number of pairs
when creating pairs, so that 4,000 pairs or less use one physical path, to distribute load on
the physical path.
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The same write-workload would be used in the reverse direction in a disaster recovery scenario.
Therefore, when planning Continuous Access Synchronous for disaster recovery, the same
number of secondary-to-primary data paths should be set up as the primary-to-secondary copy
paths for normal operations. Reverse direction paths must be set up independently of the
primary-to-secondary paths.
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When you set up secondary-to-primary data paths, specify the same combination of CUs or
CU Free as were used for the primary-to-secondary paths.
Ports
Data is transferred along the data path from the initiator to the RCU target ports on the primary
and secondary system. The amount of data each of these ports can transmit is limited.
Therefore, you must know the amount of data that will be transferred (write-workload) during peak
periods. You can then ensure not only that bandwidth meets data transfer requirements, but that
a sufficient number of each system’s ports are specified as initiator and RCU target ports to handle
all workload levels.
Port attributes and requirements
Plan and define the following Fibre Channel port attributes for Continuous Access Synchronous:
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Initiator ports, which send data. One initiator port can be connected to a maximum of 64
RCU target ports. Configure initiator ports on both primary and secondary system for Continuous
Access Synchronous disaster recovery operations.
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RCU target ports, which receive data. Configure RCU target ports on both primary and
secondary system for Continuous Access Synchronous disaster recovery operations.
One secondary system port can be connected to a maximum of 16 ports on a primary system.
The number of logical paths that can be specified does not depend on the number of ports
configured for Continuous Access Synchronous.
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Target port: Connects the storage system and a host. When the host issues a write request,
the request is sent to a volume on the XP P9500 system via a target port on the storage system.
36 Planning for Continuous Access Synchronous