Dell PowerVault DR2000v - Manual (Page 20)

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.
Replication Seeding
The DR Series systems support replication seeding, which provides the ability to create a local seed and place it in a
remote system. The seed backup is a process on the source DR Series system, which collects all of the unique data
chunks from the containers and stores them on the target device. This is helpful if you have a new replication target DR
to set up, the amount of data to be replicated is very large, and the network bandwidth is low. You can seed the target
replica with the source data saved on a third party device, for example, a CIFS—mounted share, attach it to the target
DR and then get the data into the target DR. Once the seeding is complete, replication is enabled between source and
target and replication re-synchronization is done to complete any pending data transfers. Thereby, continuous
replication can be done, which reduces network traffic significantly, and data can be replicated and synced with the
target in a short amount of time.
You initiate seeding using CLI, and the data to be seeded is gathered in an organized manner and stored in the target
devices. Refer to the
Dell DR Series System Command Line Reference Guide for more information about replication
seeding support.
Reverse Replication
The concept of reverse replication is not a supported operation on DR Series systems. This is because replica
containers 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 whose
sole function is to restore data from an archival target. For example, data could be replicated back to the remote site
where a data management application (DMA), or backup software, is connected to allow this data to be restored
directly.
This specific type of case applies only to configurations where data is backed up from a remote location to a local
container, and then replicated over a WAN to a replica container that is backed up to tape. The data needs to be
restored from the tape backup to the original location; first back to a DR Series system replica container, and then back
to the original source location of the data on the other side of the WAN link.
NOTE: If you choose to use this alternate workaround method, you must set up a new data storage unit in the
DMA, and import the images before a restore to the original location can occur.
To leverage this type of deduplication across the WAN, complete the following:
1. Make sure that the replication operation has completed (between source and target).
2. Delete the current replication relationship, and re-create a replication relationship (reversing the source and target
roles).
3. Restore data to the original source container (now the target).
4. Make sure that the replication operation has completed.
5. Delete the replication relationship and re-create a replication relationship (restoring original source and target
destinations).
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