Understanding Remote Backups

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In an effort to centralize backup management and keep costs down, many organizations are attempting to protect remote facilities by backing up data across their wide area networks. This will often create a scenario where the organization is transferring large amounts of data over DSL, Cable, and MPLS T-1 connections. Unmitigated, this deployment will create lengthy backup windows and will consume so much of the organization’s operational bandwidth, that other services that rely on that wide area network will be impacted. Remote backup is only viable when bandwidth is not a concern, data sets are very small, or when the organization employs a technology that reduces the amount of data sent across the wide area network.

The Barracuda Backup Agent uses source deduplication, also known as client-side deduplication, to allow organizations to easily backup and protect remote systems. During backup, the local Agent Database keeps track of unique parts being sent to the remote Barracuda Backup appliance. Data is indexed and sent compressed to the appliance, where it is decompressed and analyzed against data already stored on the local appliance, as shown in Figure 1.

Figure 1. Deduplication at the Source

Organizations protecting their servers with the Backup Agent need to complete a full backup and thereafter only changes are sent to the Barracuda appliance. Though only incremental changes need to be saved, Barracuda can recover a single file or an entire server from any scheduled backup.

After the initial server backup, Barracuda uses Microsoft’s USN journal to keep track of changes on the local system. This reduces seek time to find new data because the local Backup Agent reads the journal log file to find new or changed data, as shown in Figure 2. New or modified data is then deduplicated on the local system and sent compressed to the appliance.

Initial Backup

Figure 2. Tracking Changes.

Subsequent Backup

Once the deduplicated data is added to the local Barracuda Backup appliance from the remote sites, the deduplicated data is compared again across all data sources on the local appliance. If duplicate entries are found, the appliance stores a single copy of the data on the local appliance. This deduplication method is called global deduplication. Organizations that store multiple copies of data benefit from this deduplication method.

Table 1. Minimum Bandwidth Requirements.

Table 1 lists the recommended minimum bandwidth for backup. Actual requirements will vary based on your environment, and must be analyzed by all necessary parties to define the recovery point objective (RPO) and the recovery time objective (RTO) for remote sites. Network connections between sites must be stable and have minimal packet loss.