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Veritas NetBackup™ Administrator's Guide, Volume I

Last Published: 2019-07-01

Product(s): NetBackup (8.2)

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 master.

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.

Figure: Cascading Auto Image Replication

In the cascading model, the originating master server for Domain 2 and Domain 3 is the master server in Domain 1.

Note:

When the image is replicated in Domain 3, the replication notification event indicates that the master server in Domain 2 is the originating master server. However, after the image is imported successfully into Domain 3, NetBackup correctly indicates that the originating master server is in Domain 1.

The cascading model presents a special case for the Import SLP that replicates the imported copy to a target master. (This master server that is neither the first nor the last in the string of target master 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 master 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.

Import operation criteria

Import operation in a cascading model

The first operation must be an import operation.

Same; no difference.

A replication to target master 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 master. 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.

Figure: Cascading replications to target master servers, with various target retentions