HP XP7 Storage - Manual (Page 49)

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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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When you set up remote-to-local data paths, specify the same path group ID as specified for
the local-to-remote paths.
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You can reverse the local-to-remote data path to the remote-to-local direction using the PPRC
TSO CESTPATH and CDELPATH commands and system option mode 114. This can be done
even if no remote-to-local data path was previously set up. When system option mode 114 is
enabled, these commands change the port configuration automatically.
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 requirements
Note the following:
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One secondary system port can be connected to a maximum of 16 ports on a primary system.
The number of remote paths that can be specified does not depend on the number of ports
configured for Continuous Access Synchronous Z. You can specify the number of remote paths
for each remote connection.
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XP7 automatically configures a Fibre Channel port as an initiator or RCU target in response
to the TSO CESTPATH and CDELPATH commands. See system option mode 114 in
“S-VOL
Read and other system options” (page 29) .
However, make sure not to run the CESTPATH and CDELPATH commands to configure a Fibre
Channel port at the same time that the SCSI path definition function for LUN Manager is in
use.
Port attributes
Plan and define the following Fibre Channel port attributes for Continuous Access Synchronous Z:
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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 Z 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 Z disaster recovery operations.
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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 XP7 system via a target port on the storage system.
Target ports must be configured on the primary system for Continuous Access Synchronous Z
operations.
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External port: Required for External Storage copy operations. This port is not used for
Continuous Access Synchronous Z copy operations. This port can be changed to a target,
initiator, or RCU target port.
Data path requirements and configurations 49