Dell DR4000 Administrator's Manual page 15

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NOTE:
It is important to distinguish the difference between data that has been
processed by backup and data that has been processed by replication, since
backup saves a copy of data that remains unchanged for a long period of time.
Replicas on the other hand are frequently updated and can quickly lose any
historical state. The DR4000 system can be considered 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. Replication
in the DR4000 system involves the use of a replication relationship between a
pair of DR4000 systems, a source and a target system.
However, if the source and target systems in a replication pair are in different
Active Directory (AD) domains, then data that resides on the target system
may not be accessible. When AD is used to perform authentication for
DR4000 systems the AD information is saved with the file, which restricts
user access to the data based on type of AD permissions in place.
NOTE:
This same authentication information is replicated to the target DR4000
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.
Reverse Replication
The concept of reverse replication is not supported on DR4000 systems. This
is because replica containers are always in a R-O (read-only) mode on the
DR4000 system, this not making write operations a 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 agent (DMA) is connected to allow this data
to be restored directly.
This specific 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 DR4000 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.
D E L L C O N F I D E N T I A L – P R E L I M I N A R Y 4 / 5 / 1 2 - F O R P R O O F O N LY
Understanding the DR4000 System
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