HP StorageWorks XP Remote Web Console Software - Manual (Page 14)

Control Units (MCUs and RCUs)
The main control unit (MCU) and remote control unit (RCU) control TrueCopy for Mainframe
operations:
•
The MCU is the control unit (CU) in the main storage system which controls the M-VOLs of the
TrueCopy for Mainframe pairs. The Remote Web Console computer must be LAN-attached to
the MCU of each TrueCopy for Mainframe pair. The MCU communicates with the RCU via
the dedicated remote copy connections. The MCU controls the host I/O operations to the
TrueCopy for Mainframe M-VOLs as well as the TrueCopy for Mainframe initial copy and
remote copy operations between the M-VOLs and R-VOLs. The MCU also manages the
TrueCopy for Mainframe pair status and configuration information.
•
The RCU is the CU in the remote storage system which controls the R-VOLs of the TrueCopy
for Mainframe pairs. The RCU assists in managing the TrueCopy for Mainframe pair status
and configuration (for example, rejects write I/Os to TrueCopy for Mainframe R-VOLs). The
RCU executes the remote copy operations issued by the MCU. The secondary Remote Web
Console computer should be attached to the RCUs at the remote site on a separate LAN. The
RCUs should also be attached to a host system to allow sense information to be reported in
case of a problem with a secondary volume or remote storage system and to provide disaster
recovery capabilities.
The MCU and RCU can be defined separately for each TrueCopy for Mainframe pair. The HP disk
array CU can function simultaneously as an MCU for one or more M-VOLs and as an RCU for one
or more R-VOLs, provided the remote copy connections and ports are properly configured. The
HP disk array provides two logical disk controllers (LDKC). Each LDKC provides up to 255 logical
CUs (00-FE), with each CU controlling up to 256 logical devices (LDEVs).
TrueCopy for Mainframe operations can be performed on all logical devices (LDEVs) without the
command device for Business Continuity Manager in all logical CUs. The TrueCopy for Mainframe
software allows you to select the desired CU in the connected MCU and specify the desired CU
in the RCU. For detailed information about the command device for Business Continuity Manager,
see the user documentation for Business Continuity Manager.
This manual provides instructions for performing TrueCopy for Mainframe operations with the
XP24000/XP20000 Disk Arrays as the MCUs. If you are using other XP disk array models as
MCUs, see the Hitachi TrueCopy™ for z/OS User Guide: HP XP12000 Disk Array, HP XP10000
Disk Array, HP 200 Storage Virtualization System for the other model. Other HP XP disk array
models can be used as RCUs connected to the XP24000/XP20000 Disk Arrays for TrueCopy for
Mainframe Synchronous and/or Asynchronous operations.
CAUTION: If you are creating a TrueCopy for Mainframe pair with different series of storage
systems (for example, HP 24000/20000 Disk Array or XP12000/10000 Disk Array), make sure
that each storage system has a unique serial number. It is possible that a serial number overlap
could occur (although this would be extremely rare). If you have two storage systems with the same
serial number and you need to configure remote copy pairs between the two storage systems,
contact your HP service representative for assistance.
Pairs (M-VOLs and R-VOLs)
TrueCopy for Mainframe performs remote copy operations for pairs established by the user. Each
TrueCopy for Mainframe pair consists of one main volume (M-VOL) and one remote volume (R-VOL)
which are located in different storage systems. The TrueCopy for Mainframe M-VOLs are the primary
volumes which contain the original data, and the TrueCopy for Mainframe R-VOLs are the secondary
or mirrored volumes which contain the backup or duplicate data. The main and remote volumes
must have the same format and capacity.
During normal TrueCopy for Mainframe operations, the M-VOL remains available to all hosts at
all times for read and write I/O operations. The RCU rejects all I/Os to an R-VOL. The
“R-VOL
14 About TrueCopy for Mainframe Operations