HP XP7 Storage - Manual (Page 142)

Figure 18 3-data-center cascade configuration
Failure recovery occurs as follows:
•
If a failure occurs at the Cnt Ac-S Z P-VOL, business continues because data in the Cnt Ac-J Z
S-VOL is restored to the production system via the intermediate volume, if needed. Update
sequence integrity is ensured.
•
If a failure occurs at both Cnt Ac-S Z P-VOL and S-VOL, an implemented disaster recovery
plan would re-direct host activities to the Cnt Ac-J Z S-VOL.
See “Recovery for 3 Cnt Ac-J Z/Cnt Ac-S Z DC cascade configuration ” (page 108) for recovery
information and procedures.
Prerequisite information for 3DC cascade
•
XP7 must be installed at the local, Cnt Ac-S Z intermediate, and Cnt Ac-J Z remote sites.
•
Business Continuity Manager is recommended at all sites.
•
Remote Web Console is required at all sites.
Host application ◦
◦ Cnt Ac-S Z
◦ Cnt Ac-S Z primary volume (P-VOL), the primary production volume
◦ Cnt Ac-S Z fence level must be Data (CRIT=Y (ALL)).
•
The intermediate site requires the following:
Cnt Ac-S Z ◦
◦ Cnt Ac-J Z
◦ Cnt Ac-S Z S-VOL = Cnt Ac-J Z P-VOL
◦ Cnt Ac-J Z master journal volume
•
The remote site requires the following:
Cnt Ac-J Z ◦
◦ Cnt Ac-J Z S-VOL
◦ Cnt Ac-J Z remote journal volume
•
Differential data is used to re-synchronize a suspended Cnt Ac-S Z or Cnt Ac-J Z pair.
•
When the Cnt Ac-S Z pair is resynchronized, the Cnt Ac-J Z pair in Duplex or Pending status
is automatically split by the system.
•
The fence level of the Cnt Ac-S Z P-VOL must be Data.
•
3DC cascade is not supported for multiple primary and secondary systems. The Cnt Ac-J Z or
Cnt Ac-S Z pair in this configuration would be suspended when the status became PAIR or
COPY.
142 Configurations with Continuous Access Synchronous Z