Similarly, consider another example of the application package is running on DC1 and the data is being replicated to DC3 from DC1 (i.e. Multi-target topology). Upon the failure of application on all nodes in DC1, the application package fails over to a node in DC2. As part of package startup, the data replication between DC1 and DC2 is reversed and the data starts replicating from DC2 to DC1. The replication to DC3 will be continued from DC1 (i.e Multi-hop topology). The same Active-CAJ pair (DC1-DC3 pair) is used even after the failover to replicate the data to DC3 as shown in Figure 84 (page 465).
Figure 84 Package Failover with data being replicated to DC3 from DC1
NOTE: When the application package is running on DC1 and the data is being replicated to DC3 from DC1 (i.e. Multi-Target topology) as shown in Figure 9, upon the failure of all nodes in DC1, the application package fails over to a node in DC2. As part of the package startup, the data replication between DC1 and DC2 is reversed and the data starts replicating from DC2 to DC1. This suspends the Active-CAJ pair internally by the firmware. In this case of all DC1 nodes failed, 3DC DR software is unable to resync the Active-CAJ pair whereas in other cases it re-syncs Active-CAJ pair automatically. 3DC DR software logs appropriate messages in the package configuration file and sends the notification to the user if DGM is configured. The user has to manually resync the Active-CAJ pair in this scenario.
During the failover of a package from DC1 to DC2, the Delta Resync pair is re-synchronized only when it is not able to replicate the data over both DC1-DC2 pair and Active-CAJ pair (i.e. only when data is not protected at any other site). Only in this scenario, Active-CAJ pair is changed. For example, the application package is running on DC1 and data is being replicated to DC3 from DC1. Upon entire DC1 failure, the application package fails over to a node in DC2. Since data cannot be replicated from DC2 to DC1, it is not possible to replicate data to DC3 using the existing Active-CAJ pair. To replicate data to DC3, the Delta Resync pair between DC2 and DC3 is resynchronized automatically during the package startup. This starts replicating the data from DC2 to DC3 and the device group between DC2 and DC3 becomes new Active-CAJ pair as shown in Figure 85 (page 466).
Automatic Failover between DC1 and DC2 465