content_image/971379.jpg
Figure 5-5 shows an optional host connection that can be established to remote Cluster 2 using DWDM or channel extenders. 

<img src='content_image/971379.jpg'>

## Three-cluster high availability production site and DR 

This model was adopted by many clients. In this configuration, two clusters are in the production site (same building or separate location within metro area) and the third cluster is remote at the DR site. Host connections are available at the production site (or sites). 

In this configuration, each TS7700D replicates to its local TS7700D peer and the remote TS7700. Optional copies in both TS7700D clusters provide high availability and cache access time for the host accesses. At the same time, the remote TS7700 provides DR capabilities and the remote copy can be remotely accessed, if needed. 

