NOTE: The DR Series system software includes version checking that limits replication only between other DRSeries systems that run the same system software release version. If versions are incompatible, the administratorwill be notified by an event.NOTE: It is important to distinguish the difference between data that has been processed by backup, and data thathas been processed by replication. This is because backup saves a copy of data that generally remainsunchanged for a long period of time.Targets with replication data are read-only, and are updated with new or unique data during scheduled or manualreplications. The DR Series system can be considered to act as a form of a storage replication process in which thebackup and deduplication data is replicated in real-time or via a scheduled window in a network environment. In areplication relationship between two DR Series systems, this means that a relationship exists between a pair of systems.One system acts as the source and the other as a target in this replication pair (for example, acme-west and acme-east).When this type of relationship exists between distinct containers on two distinct DR Series systems, it can beconsidered bidirectional in the sense that:• The West1 container on the acme-west source system can replicate data to a separate East1 container on theacme-east target system.• The East2 container on the target acme-east system can also replicate data back to the West2 container on thesource acme-west system.This form of replication involves separate containers on two distinct DR Series systems. Target containers in replicationmust always act as read-only, while sources containers can act as read-write. Unlike NFS and CIFS containers, OST andRDS container replication is handled by the two supported Data Management Applications (DMAs) on media servers.For more information on OST, see Understanding OST. For more information on RDS, see Configuring and Using RapidData Storage.NOTE: OST and RDS containers are categorized as Rapid Data Access (RDA) containers in DR Series systems.The DR Series system supports the 64:1 replication of data (32:1 if on DR4X00), whereby up to 64 source DR Seriessystems can write data to different individual containers on a single, target DR Series system. This supports the usecase where branch or regional offices can each write their own data to a separate, distinct container on a maincorporate DR Series system.NOTE: Be aware that the storage capacity of the target DR Series system is directly affected by the number ofsource systems writing to its containers, and by the amount being written by each of the source systems.However, if the source and target systems in a replication pair are in different Active Directory (AD) domains, then thedata that resides on the target system may not be accessible. When AD is used to perform authentication for DR Seriessystems, the AD information is saved with the file. This can act to restrict user access to the data based on the type ofAD permissions that are in place.NOTE: This same authentication information is replicated to the target DR Series system when you havereplication configured. To prevent domain access issues, ensure that both the target and source systems reside inthe same Active Directory domain.Reverse ReplicationThe concept of reverse replication is not a supported operation on DR Series systems. This is because replicacontainers are always in a R-O (read-only) mode on the DR Series system, thus making write operations a non-supported operation.Under very specific conditions, it might be possible for replica containers to support a type of write operation whosesole function is to restore data from an archival target. For example, data could be replicated back to the remote sitewhere a data management application (DMA), or backup software, is connected to allow this data to be restoreddirectly.20
