Overview of 3DC cascade configuration

In the 3DC cascade configuration, data centers are placed at three sites, the primary site, intermediate site, and secondary site. One VSP G800, VSP F800, or VSP G1000 is required for each site. HUS VM is not supported in 3DC cascade configurations.

TC pair is created by using the production volume at the primary site as P-VOL and the volume at the intermediate site near the primary site as S-VOL. Furthermore, a UR pair is created by sharing TC S-VOL as UR P-VOL and uses the volume at the secondary site as S-VOL. To make the I/O response time shorter, place the intermediate site near the primary site. The I/O response time to the host is the total of the TC response time and the journal data creation time at the intermediate site. The following illustration describes this configuration. For details about setting up the 3DC cascade configuration, see 3DC cascade configuration.