Cascading Auto Image Replication model
Replications can be cascaded from the originating domain to multiple domains. Storage lifecycle policies are set up in each domain to anticipate the originating image, import it and then replicate it to the next target primary.
Figure: Cascading Auto Image Replication represents the following cascading configuration across three domains.
The image is created in Domain 1, and then replicated to the target Domain 2.
The image is imported in Domain 2, and then replicated to a target Domain 3.
The image is then imported into Domain 3.
In the cascading model, the originating primary server for Domain 2 and Domain 3 is the primary server in Domain 1.
Note:
When the image is replicated in Domain 3, the replication notification event indicates that the primary server in Domain 2 is the originating primary server. However, after the image is imported successfully into Domain 3, NetBackup correctly indicates that the originating primary server is in Domain 1.
The cascading model presents a special case for the Import SLP that replicates the imported copy to a target primary. (This primary server that is neither the first nor the last in the string of target primary servers.)
The Import SLP must include at least one operation that uses a Fixed retention type and at least one operation that uses a Target Retention type. So that the Import SLP can satisfy these requirements, the import operation must use a Target Retention.
Table: Import operation difference in an SLP configured to replicate the imported copy shows the difference in the import operation setup.
Table: Import operation difference in an SLP configured to replicate the imported copy
Import operation criteria | Import operation in a cascading model |
|---|---|
The first operation must be an import operation. | Same; no difference. |
A replication to target primary must use a Fixed retention type | Same; no difference. |
At least one operation must use the Target retention. | Here is the difference: To meet the criteria, the import operation must use Target retention. |
The target retention is embedded in the source image.
In the cascading model that is represented in Figure: Cascading Auto Image Replication, all copies have the same Target Retention - the Target Retention indicated in Domain 1.
For the copy in Domain 3 to have a different target retention, add an intermediary replication operation to the Domain 2 storage lifecycle policy. The intermediary replication operation acts as the source for the replication to target primary. Since the target retention is embedded in the source image, the copy in Domain 3 honors the retention level that is set for the intermediary replication operation.
