HP StorageWorks XP Remote Web Console Software - Manual (Page 15)

system). This virtual storage system is called a logical DKC or an LDKC (logical disk controller).
There is one LDKC in the storage system, and number 00 is assigned to the LDKC.
Each LDKC controls 255 CUs. However, the number of CUs that can be used for storage system
program products is up to 255. Therefore, the maximum number of volumes that can be used for
storage system program products is 65,280 volumes for an LDKC.
Main and Remote Control Units (Primary Storage Systems and Secondary Storage
Systems)
The main control unit (primary storage system) and remote control unit (secondary storage system)
control XP Continuous Access Journal operations:
•
The primary storage system is the control unit in the primary storage system controls the primary
data volume of the XP Continuous Access Journal pairs and master journal volume. The Remote
Web Console computer must be LAN-attached to the primary storage system. The primary
storage system communicates with the secondary storage system via the dedicated remote
copy connections.
•
The primary storage system controls the host I/O operations to the XP Continuous Access
Journal primary data volume and the journal obtain operation of the master journal volume,
as well as the XP Continuous Access Journal initial copy and update copy operations between
the primary data volumes and the secondary data volumes.
•
The secondary storage system has control units that control the secondary data volume of the
XP Continuous Access Journal pairs and restore journal volume. The secondary storage system
controls copying journals and restoring journals to secondary data volumes. The secondary
storage system assists in managing the XP Continuous Access Journal pair status and
configuration (for example, rejects write I/Os to the XP Continuous Access Journal secondary
data volumes).
•
The secondary storage system issues the read journal command to the primary storage system
and executes copying journals. The secondary Remote Web Console computer should be
connected to the secondary storage systems at the secondary site on a separate LAN. The
secondary storage systems should also be attached to a host system to allow sense information
to be reported in case of a problem with a secondary data volume or secondary storage
system, and to provide disaster recovery capabilities.
The storage system can function simultaneously as a primary storage system for one or more primary
data volumes, and as an secondary storage system for one or more secondary data volumes,
provided the remote copy connections and Fibre Channel interface ports are properly configured.
XP Continuous Access Journal allows you to specify the secondary storage system from the connected
primary storage system. XP Continuous Access Journal operations can be performed on all LDEVs
except for the storage system command device. For further information on the storage system
command device, see the HP StorageWorks RAID Manager User Guide.
NOTE: When you configure an XP Continuous Access Journal group pair, you have to specify
the serial numbers of the primary storage systems and secondary storage systems. You have to
specify different serial numbers for the primary storage system and secondary storage system for
the same XP Continuous Access Journal group pair. If you have to specify the same serial number
for both systems, contact your HP service representative.
Consistency Groups
XP Continuous Access Journal consistency group numbers are the same as XP Continuous Access
Asynchronous consistency group numbers. Therefore, you can create an XP Continuous Access
Journal pair using the consistency group numbers from RAID Manager, as is the case with XP
Continuous Access Asynchronous. In XP Continuous Access Journal operations, the consistency
group numbers that are specified from RAID Manager are assigned to the journal group numbers.
XP Continuous Access Journal Components 15