HP XP Racks - Manual (Page 41)

4x4x4 Delta Resync configuration
This configuration is a combination of a 4x4 configuration and a Delta Resync configuration.
Between the primary site and the local site, a Cnt Ac-S Z copy group is used. Between the primary
site and the remote site, the a Cnt Ac-J Z group defined as an extended consistency group (EXCTG)
that stays in the Delta Resync waiting status is used. Between the local site and the remote site, a
Cnt Ac-J Z group that defined the EXCTG (which is in the Delta Resync waiting status) is used. By
performing a Delta Resync when the operation site is changed from the primary site to the local
site, the configuration can be switched to a 4x4x4 Delta Resync configuration with the local site
as the origin.
Although the Delta Resync configurations cannot preserve consistency across multiple storage
systems, 4x4x4 Delta Resync configurations can preserve consistency across multiple storage
systems in an EXCTG. The following figure shows a 4x4x4 Delta Resync configuration.
Data center configurations 41