HP StorageWorks XP Remote Web Console Software - Manual (Page 11)

Remote copy connections
Remote copy connections are physical paths MCUs use to communicate with RCUs. The number
of physical paths in the MCU is limited to eight per logical CU image. MCUs and RCUs are
connected via Fibre Channel interface cables.
When Fibre Channel interface connections are used, switches are required for distances greater
than 0.5 km (1,640 feet). Distances up to 1.5 km (4,920 feet, 0.93 miles) are supported with dual
switches utilizing shortwave connections. Distances up to 10 km (6.2 miles) are supported using
dual switches with longwave connections. Distances up to 30 km (18.6 miles) are supported using
dual switches with longhaul connections. Distances up to 100 km are supported by using dual
switches with DWDM. See
“Fibre Channel remote copy connections” (page 35) for further
information about installing and configuring Fibre Channel remote copy connections.
The MCU-to-RCU remote copy configuration for XP Continuous Access Asynchronous has different
requirements than the XP Continuous Access Synchronous configuration, as follows:
•
XP Continuous Access Synchronous supports 1-to-n and n-to-1 remote copy connections (where
n≤4). One MCU can be connected to as many as four RCUs. One RCU can be connected
to as many as four MCUs (one MCU/RCU = one physical CU, including all sixteen CU images).
•
XP Continuous Access Asynchronous supports 1-to-1 remote copy connections within the same
consistency group. P-VOLs and S-VOLs of pairs in a consistency group must be within one
physical MCU and one physical RCU. This configuration ensures backup integrity for a data
set spread across multiple volumes within one array (such as large databases).
XP Continuous Access Asynchronous 1-to-n and n-to-1 (where n ≤ 4) configurations (one main
disk array and multiple remote disk arrays) are valid for XP Continuous Access Asynchronous
if all volumes belonging to a single consistency group are only 1-to-1.
•
With direct-connect Fibre Channel (no switch), fibre remote copy supports 1-to-1 remote copy
connections. One array as an MCU can be connected to only one array as an RCU via optical
fibre cables. For CU images within one array, 1-to-4 and 4-to-1 remote copy connections are
supported via direct connects or an FC switch.
One MCU port (initiator port) can be connected to 64 RCU ports (RCU target ports). One RCU
port can be connected to 16 MCU ports. However, the number of logical paths that can be specified
does not depend on the number of connectable RCU or MCU ports.
HP strongly recommends you establish at least two independent remote copy connections (one per
cluster) between each MCU and RCU to provide hardware redundancy for this critical
communications path.
NOTE: To recover data from a disaster, prepare the RCU-MCU paths in addition to the usual
MCU-RCU paths. For more information, see Registering RCUs (Add RCU) .
When you set the RCU-MCU path, you must also specify:
•
The same combination of CU images as when you set the MCU-RCU path if you set the
MCU-RCU path and specify the CU image.
•
CU Free if you set the MCU-RCU path and specify CU Free.
Initiator ports and RCU target ports
Initiator ports are dedicated Fibre Channel interface ports on the main disk array (MCU) to which
RCUs (RCU target ports) are connected. Initiator ports connect to RCUs to send write I/O operations
directly to RCUs. You can configure Fibre Channel interface ports of the array as initiator ports.
Use the Port Change operation (see
“Port change operation” (page 80) ) to change the configuration
of the array Fibre Channel ports (ordinary target port, initiator port, or RCU target port) as needed.
Components 11