HP XP Continuous Access Software - Manual (Page 35)

Journal obtain in Continuous Access XP Synchronous secondary sites
To perform the DC2-to-DC3 delta resync operation when a DC1 failure occurs, you must first obtain
journal data in DC2 the Continuous Access XP Synchronous secondary site with a 3DC multi-target
configuration. To create a Continuous Access XP Journal pair for an eventual delta resync operation,
specify the DC2 Continuous Access XP Synchronous S-VOL in the Continuous Access XP Synchronous
secondary site as the primary data volume, and specify the DC3 data volume in the Continuous Access
XP Journal secondary site as the secondary data volume.
When creating the contingency Continuous Access XP Journal pair for use with a DC2-to-DC3 delta
resync operation, differential data for data volumes in the Continuous Access XP Synchronous primary
and secondary sites is stored as MCU journal data in journal volumes in the DC2 Continuous Access XP
Synchronous secondary site. Figure 7 shows an example.
Figure 7 Delta resync contingency configuration in a 3DC multi-target topology (before
a failure occurs)
As shown in Figure 7 , a Continuous Access XP Journal contingency pair created with the delta resync
option is defined as a pair, but no copy operation is performed (HOLD status). No copy operations are
performed until a failure occurs and a delta resync operation is needed. There are several requirements
to create a Continuous Access XP Journal pair for delta resync operations, such as specifying an unused
mirror unit ID. For information about requirements for creating Continuous Access XP Journal pairs for
delta resync operations, see Requirements for creating Continuous Access XP Journal pairs for delta
resync operations .
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