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7-2 Chapter 7 Using Extended Consistency Groups
Hitachi Universal Replicator for IBM /OS User’s Guide
If you want to perform remote copy operations between more than one
primary storage system and more than one secondary storage system, you
must register journal groups in extended consistency groups (abbreviated as
EXCTG). To register journal groups in extended consistency groups, use the
EXCTG Operation window.
• Displaying the EXCTG Operation window (see section EXCTG Operation
Window)
• Registering journal volumes in an extended consistency group (see the
next section)
• Removing journal volumes from an extended consistency group (see
section
Removing Journal Groups from an Extended Consistency Group)
Registering Journal Groups in an Extended Consistency
Group
If you want to perform remote copy operations between more than one
primary storage system and more than one secondary storage system, you
must register journal groups in an extended consistency group, which is
abbreviated as EXCTG.
• Notes on configuring an extended consistency group:
You must confirm that the journal groups to be registered must be in
Active or Stop status.
You must not register master and restore journal groups in the same
extended consistency group.
• Configuring primary EXCTG:
You need to 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. If you reverse the copy direction when no primary EXCTG is
configured, data update sequence will be maintained on journal group basis,
but not on extended consistency group basis.
For details on reversing copy direction, see section
Transferring Operations
Back to the Primary Site.
• Configuring secondary EXCTG:
You need to configure a secondary EXCTG when you use more than one
primary storage system and more than one secondary storage system. URz
uses the secondary EXCTG to maintains data update sequence of master
journal groups that are paired with restore journal groups in secondary
EXCTG. If no secondary EXCTG is configured, data update sequence will
not be maintained, and data consistency will not be maintained between
the primary storage systems and the secondary storage systems.
To register journal groups in an extended consistency group: