HP StorageWorks XP Remote Web Console Software - Manual (Page 25)

Main and Remote Control Units
The main control unit (primary storage system) and remote control unit (secondary storage system)
control URz operations:
• The primary storage system is the control unit in the primary storage system which controls
the primary data volume of the URz pairs and master journal volume. The XP Remote Web
Console remote console PC 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 URz primary
data volume and the journal obtain operation of the master journal volume as well as the URz
initial copy and update copy operations between the primary data volumes and the secondary
data volumes.
• The secondary storage system is the control unit in the secondary storage system which controls
the secondary data volume of the URz pairs and restore journal volume. The secondary storage
system controls copying of journals and restoring of journals to secondary data volumes. The
secondary storage system assists in managing the URz pair status and configuration (e.g., rejects
write I/Os to the URz secondary data volumes). The secondary storage system issues the read
journal command to the primary storage system and executes copying of journals. The secondary
XP Remote Web Console PC 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 XP disk array can function simultaneously as a primary storage system for one or more primary data
volumes and as a secondary storage system for one or more secondary data volumes, provided the
remote copy connections and fibre-channel interface ports are properly configured. The URz software
allows you to specify the secondary storage system from the connected primary storage system. URz
operations can be performed on all LDEVs except for the XP disk array command device. For further
information on the XP disk array command device, please refer to the XP for Business Continuity Manager
Software user’s guide.
When you configure a URz journal group pair, you have to specify the serial numbers of primary storage
systems and secondary storage systems. You have to specify the different serial numbers of primary
storage system and secondary storage system for the same URz journal group pair. If you have to specify
the same serial number, please contact your HP account team.
Journal Group
Journal group consists of two or more data volumes and journal volumes. It is a feature that allows you to
sort multiple data volumes and journal volumes into collective units to tailor URz to meet your unique
business needs. The journal group in the primary storage system is referred to as the master journal
group. The journal group in the secondary storage system is referred to as the restore journal group.
The data volumes in the master journal group are also called the primary data volumes. The journal
volumes in the master journal group are called the master journal volumes. The data volumes in the
restore journal group are similarly called the secondary data volumes. The journal volumes in the restore
journal group are called the restore journal volumes.
The data update sequence from the host is managed per the journal group. The data update sequence
consistency between the master and restore journal groups to be paired is maintained and ensured. The
master and restore journal groups are managed according to the journal group number. The journal
numbers of master and restore journal groups that are paired can be different. One data volume and one
journal volume can belong to only one journal group.
Caution: Data volumes and journal volumes that belong to different LDKCs cannot coexist in the same
journal group.
For detailed information about the specification of journal groups, see
Table 18 on page 63.
Hitachi Universal Replicator for z/OS user guide for XP12000/XP10000 Disk Arrays and SVS 200 25