Dell EqualLogic replication is a backup solution which takes a point-in-time copy of a storage volume and places it in another EqualLogic group, which is usually geographically separate from the original

After the first copy has been moved, each subsequent copy is comprised of the changes that have taken place on the volume since the last replica.

Effectively, this means that after your first replica, if you only change 1GB of data, 1GB of data will replicate for your second replica. This efficiency allows you to replicate faster and more frequently.

Features
  Basic Plus
Secure, unmetered layer 2 connection between your storage and ours
Our enclosure presented to yours as a replication partner to receive the volumes you send
Stored information on our EqualLogic devices presented to you
Cheaper solution than buying an additional Dell EqualLogic device
No need to worry about data transfer bills
Easily scalable
Replicated data made accessible to your co-located servers at the failover site  
No need to buy additional colocation space for failover server hardware  
Replicated data made accessible to provided virtual servers at the failover site