HP StorageWorks XP Remote Web Console Software - Manual (Page 74)

3. From journal data having the time stamp and earlier time stamps, the subordinate DKCs restore
all journal data that have not been restored, in the order of the sequence numbers.
Hardware Configuration (When More Than One Primary and Secondary
Storage Systems are Used)
This section explains hardware configuration when more than one primary and secondary subsystem are
used.
It is recommended that Business Continuity Manager is installed on the host in the primary and secondary
sites. Storage Navigator PCs must be installed in both of these sites. Also, disk subsystem settings must be
made so that Business Continuity Manager can be used. For detailed information about settings required
for using volumes in a remote site, please refer to Business Continuity Manager User’s Guide.
Up to four primary subsystems and up to four secondary subsystems can be used. For example, you can
use four primary subsystems and four secondary subsystems. Also, you can use two primary subsystems
and one secondary subsystem.
The supervisor DKC and subordinate DKCs must be mutually connected in the secondary site, so that
arbitration processing can be performed. Also, remote command devices must be created in the
supervisor DKC. For details on secondary subsystems connections and remote command devices, and the
Universal Volume Manager User’s Guide.
Setup Procedure (When More Than One Primary and Secondary Subsystem
are Used)
1. Install URz on subsystems in the primary and secondary sites.
2. Make settings on ports and journal groups of the subsystems in the primary and secondary sites.
3. Create command devices in secondary subsystems.
4. Create remote command devices in the supervisor DKC, and then map them to command
devices in the subordinate DKCs.
5. Create URz volume pairs.
6. With the remote command devices created in step 4, use the supervisor DKC to register journal
groups of secondary subsystems in an extended consistency group.
Extended Consistency Groups
To perform remote copy operations between more than one primary storage system and more than one
secondary storage systems while maintaining data consistency, you must register journal groups in an
extended consistency group (abbreviated as EXCTG). An extended consistency group is a collection of
journal groups. This manual uses the term "primary EXCTG" to refer to an extended consistency group for
primary storage systems. This manual also uses the term "secondary EXCTG" to refer to an extended
consistency group for secondary storage systems.
To perform remote copy operations between more than one primary storage system and more than one
secondary storage systems while maintaining data consistency, you must configure a secondary EXCTG.
Also, it is recommended that you configure a primary EXCTG, because the primary EXCTG will be
necessary if you need to reverse the primary and secondary sites after a failure occurs. You can register
journal groups of up to four different storage systems in the same extended consistency group, but you
cannot register one journal group in different extended consistency groups. The following table explains
specifications of extended consistency groups:
74 Preparing for Universal Replicator z/OS Operations