Two main backup environment topologies are as follows:  GLYPH<SM590000> Single domain backup environment GLYPH<SM590000> Multiple domain backup environment A single domain backup environment shares a catalog across the primary and DR sites.  Its entries are visible for both servers always. In a single domain environment, the backup  application is fully aware of the whereabouts and status of the cloned cartridges.  Note:  The single domain backup environment works well with Symantec NetBackup,  but does not work with Tivoli Storage Manager. A multiple domain environment requires the user to recover the DR backup server by  using a copy of the catalog or DB that matches the replicated repository cartridges that  are set before restoring their replicated data from the ProtecTIER system at the DR site.  Remote cloning is the process of using a secondary (DR) site to clone cartridges. You can  use ProtecTIER replication to offload tape cloning to your secondary site. Many users  replicate their data from the primary site to the secondary (DR) site, and then move it from the  disk-based repository on to physical tape cartridges for long-term retention.  One of the advantages of this practice at the secondary site is that it shifts the burden of  cloning to physical tape from the production environment to the DR site location. The DR site  cloning operation uses the cartridge replicas at the ProtecTIER VTL shelf of the destination.  The process imitates the commonly used physical process for the transportation of physical  cartridges from the primary site to a DR site. This feature is effective in single domain backup deployments because in these environments  the backup application servers at both sites share the catalog and can be concurrently  connected to the ProtecTIER systems. The replication visibility switch control feature is used  in these environments. The cartridges to be cloned are moved from the primary repository to  the secondary repository and then cloned to physical tapes. 12.7 Remote cloning of virtual tapes Chapter 12. Backup management introduction  185