22.1 Disaster recovery operations 22.2 ProtecTIER replication overview Disaster recovery (DR) is the process of recovering production site data at a secondary (or  tertiary) location. Disaster recovery is useful if a disaster occurs or a situation occurs where  the production (or primary) site goes offline. The secondary site, hub, or DR site, can take the  place of the production site until the primary site comes back online.  In ProtecTIER VTL environments, entering DR mode is done by using the ProtecTIER  Manager graphical user interface (GUI) when you are logged on to the DR ProtecTIER  system. When you enter ProtecTIER DR mode, all incoming replication and visibility switching  activities from the failed production site to the DR site (hub) are blocked. The DR node  remains eligible for local backup and restore activity. When the primary site is rebuilt or replaced, you can then use the ProtecTIER Failback  function to return the systems to their normal state and resume the backup and replication  operations. When the primary site comes back online, previously replicated and newly  created objects can be moved to the main production site by using the failback process. The  primary site then resumes its roll as a production site. Note:  The Disaster Recovery and Failback menu options are available for VTL  environments. For FSI environments, you can block the replication traffic by selecting  Replication  Control Replication traffic  in the ProtecTIER Manager GUI. This  Replication menu also provides other operations for DR purposes, such as Cloning. For details about the DR concepts for VTL and FSI, see the topic about native replication  and disaster recovery in  IBM System Storage TS7600 with ProtecTIER Version 3.3 ,  SG24-7968. ProtecTIER replication enables virtual tape cartridges (VTL mode) or file system volumes  (FSI mode) to be replicated from the primary site to secondary or multiple sites. This  capability is intended to enhance DR and business continuity (BC). Users can select some or all of their data objects to be replicated to one or more sites.  ProtecTIER replication provides DR capability and enhanced availability in accessing backed  up data for restore operations across sites. Replication can run in parallel with backup and  restore activities or in dedicated scheduled time frames. Data transfer is started based on trigger points in either on-demand continuous replication or  replication schedules. Data verification and validation is done at the DR site to ensure the  integrity of the transferred data before you make the virtual cartridge or tape available. In summary, replication works as follows: GLYPH<SM590000> Each ProtecTIER server that is a part of a replication grid has two dedicated replication  ports that are used for replication.  GLYPH<SM590000> Each ProtecTIER environment has at least one ProtecTIER server.  GLYPH<SM590000> The replication function enables ProtecTIER deployment to be distributed across sites.  Each site can have a single or clustered ProtecTIER environment.  GLYPH<SM590000> Replication is a process that transfers logical objects such as cartridges from one  ProtecTIER repository to another repository.  396  IBM ProtecTIER Implementation and Best Practices Guide