Administrator Guide

Replication

Replication is the process by which key data is saved from storage locations, with the goal of maintaining consistency

between redundant resources in data storage environments. Data replication improves the level of fault-tolerance,

which improves the reliability of maintaining saved data and permits accessibility to the same stored data.

The DR Series system uses an active form of replication that lets you configure a primary-backup scheme. During

replication, the system processes data storage requests from a specified source to a specified replica target, which

acts as a replica of the original source data. This replica can then be cascaded optionally to a third location called a

Cascaded replica for an additional copy.

NOTE

: The DR Series system software includes version checking that limits replication only between other DR

Series systems that run the same system software release version. If versions are incompatible, the administrator

is notified by an event.

NOTE

: Replication for VTL containers is not currently supported. However this feature is actively being worked on

and will be made available in a future DR Series system release.

Replicas/Cascaded replicas are read-only and are updated with new or unique data during scheduled or manual

replications. The DR Series system can be considered to act as a form of a storage replication process in which the

backup and deduplication data is replicated in real-time or via a scheduled window in a network environment. In a

replication relationship between two or three DR Series systems, this means that a relationship exists between a

number of systems. One system acts as the source and the other as a replica, with an optional third cascaded replica if

you have chosen to keep two instances of replicated data in your backup workflow.

Replication is done at the container level and is one directional from source to replica to optional cascaded replica;

however, since replication is done at the container level you can set up various containers to meet your specific

replication requirements for your specific workflow. This form of replication is supported for the CIFS, NFS, Rapid CIFS,

and Rapid NFS protocols and is fully handled by the DR Series system.

NOTE

Refer to the

Dell DR Series Interoperability Guide

for information about the maximum number of files replicated per

container at a time per DR Series system.

Unlike NFS, CIFS, Rapid NFS or Rapid CIFS containers, RDA with OST, RDA with NetVault Backup, and RDA with vRanger

container replication is handled by Data Management Applications (DMAs) media servers.

The DR Series system supports the 64:1 replication of data (32:1 if on DR4X00 and 8:1 on DR2000v), whereby up to 64

source DR Series systems can write data to different individual containers on a single, target DR Series system. This

supports the use case where branch or regional offices can each write their own data to a separate, distinct container

on a main corporate DR Series system.

NOTE

: The storage capacity of the target DR Series system is directly affected by the number of source systems

writing to its containers, and by the amount being written by each of the source systems.

If the source and target systems (replica or cascaded replica) are in different Active Directory (AD) domains, then the

data that resides on the target system may not be accessible. When AD is used to perform authentication for DR Series

systems, the AD information is saved with the file. This can act to restrict user access to the data based on the type of

AD permissions that are in place.

NOTE

: This same authentication information is replicated to the target DR Series system when you have

replication configured. To prevent domain access issues, ensure that both the target and source systems reside in

the same Active Directory domain.