Dell EMC Metro node 7.0.1 Administrator Guide

Global visibility

If the local consistency groups have their Visibility property set to both clusters (global visibility), both clusters can receive I/O from the cluster that does not have a local copy.

All writes from that remote cluster pass over the inter-cluster WAN link before they are acknowledged.

Any reads that cannot be serviced locally are also transferred across the link. This allows the remote cluster to have instant on demand access to the consistency group, but also adds additional latency for the remote cluster.

Local consistency groups with global visibility are supported in metro node Metro environments. Only local volumes can be placed into the local consistency group with global visibility. Local consistency groups with global visibility always use write-through cache mode (synchronous cache mode). I/O that goes to local consistency groups with global visibility will always be synchronous.

the following shows a local consistency group with global visibility.