Replication is the logical synchronization of backup data from one Unitrends system to another, in which the systems are connected by LAN or WAN. The originating system is referred to as the source, while the off-site system onto which the data is replicated is the target. Replication enables off-site storage of mission-critical data to protect against data loss in the event of a disaster. The source system is used to protect against loss of files, folders, and individual machines. The target system protects against loss of client data, as well as providing protection against the loss of the entire source system.
Replicated backups look like their counterparts on the source system and are restored in the same way. The target system is configured for retention while in replication view, using the same procedure as any source system (see About retention control). For a given client, you may have more than one backup group on the target, unlike legacy vaulting in which only the most recent backup is stored. As with source systems, the amount of retention on the target is dependent on space available and retention settings.
The target system can be deployed as a private cloud or as a multi-tenant cloud. The replication architecture ensures that the local source systems that replicate to a single target only have access to their data. This secure architecture is the basis of a multi-tenant architecture.
The replication process is fully managed from the target or source system. Using the replication dashboard, you can immediately gauge the status of replication by viewing active, previously completed, and pending replication jobs.
Unitrends’ replication leverages a secure tunnel based on the UDP protocol that creates a secure VPN tunnel and also provides resiliency to intermittent network failures via UDP knitting. If there is a network drop during replication, the process utilizes advanced checkpoint controls to proceed with replication at the time of failure. For details, see About secure tunnels for Unitrends systems.
The initial transfer of data from the source system to the target can occur over the WAN. However, for large data sets it is recommended to use a disk seeding mechanism to transfer the initial data set. Even with deduplication minimizing the amount of data being transferred, transfer speed is primarily governed by the size of the network pipe between the source and target systems. Seeding is also recommended in cases where available bandwidth is used for servicing end users at specific times during the day and cannot be used for replication.
Windows Instant Recovery is supported on the replication target system. See Windows Instant Recovery for more information.
The secure tunnel is used by Unitrends to create an optimized, secure, encrypted tunnel for multiple Unitrends systems. The secure tunnel offers a scalable solution for enabling multiple clients to connect to a single server process through a single UDP port.
There are two typical cases for using the secure tunnel with Unitrends systems. The first is a replication scenario where there is a target system and one or more source backup systems. In this case, the secure tunnel is configured between the target and the source systems in order to facilitate both the replication of data and the management of the systems. The second is the case where two or more systems are managed by a designated management system. With this setup, you can then perform operations for all systems from one Unitrends system interface.
The primary advantages of the secure tunnel are that it enables radically simpler firewall management (since only one port is needed between off-premise Unitrends systems) and that it enables much higher session availability because it can handle lower quality WAN lines that would typically result in session termination (through UDP-level ride-through of short-lived transient line failures).