HP StoreOnce Backup System Concepts and Configuration Guidelines (BB877-90913, November 2013)

Figure 43 N-way replication
In most cases StoreOnce VTL and StoreOnce NAS replication is the same, the only significant
configuration difference being that VTL replication allows multiple source libraries to replicate into
a single target library, NAS mappings however are 1:1, one replication target share may only
receive data from a single replication source share. In both cases replication sources libraries or
shares may only replicate into a single target. However, with VTL replication a subset of the
cartridges within a library may be configured for replication (a share may only be replicated in
its entirety).
What to replicate
StoreOnce VTL replication allows for a subset of the cartridges within a library to be mapped for
replication rather than the entire library (NAS replication does not allow this).
Some retention policies may not require that all backups are replicated, for example daily
incremental backups may not need to go offsite but weekly and monthly full backups do, in which
case it is possible to configure replication to only replicate those cartridges that are used for the
full backups.
Reducing the number of cartridges that make up the replication mapping may also be useful when
replicating several source libraries from different StoreOnce devices into a single target library at
a data center, for example. Limited slots in the target library can be better utilized to take only
replication of full backup cartridges rather than incremental backup cartridges as well.
Configuring this reduced mapping does require that the backup administrator has control over
which cartridges in the source library are used for which type of backup. Generally this is done
What to replicate 81