Synthetic Full Backup with CloudBerry Backup

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Synthetic full backup is, basically, full backup and incremental backup mixed together. In the end, you get a full backup on the storage, that's incrementally being updated, without unnecessary or outdated data. You always have your up-to-date full backup.

We have developed a synthetic full backup feature for image-based backups in CloudBerry Backup. This enhancement decreases the amount of data uploaded to the cloud and accelerates the overall process. We are going to explain the technical background and show how to use the new feature.

How Synthetic Full Backup Works

The idea of synthetic full backup came from the block-level backup. The block-level backup contains only modified image blocks which, in turn, decreases the amount of data transferred to the cloud. But avoiding data losses and making recovery faster requires regular full backups, which upload a large amount of data, even if it’s already stored in the previous copies. You can read more about this process in Block vs. Full Backup post.

Synthetic Full Backup helps to reduce the amount of data uploaded and accelerates a full backup creation. Synthetic Full Backup compares local data blocks with the cloud repository and then uploads only modified ones. Currently, existing blocks in the cloud that haven't been modified since the last full backup or the last synthetic full session are automatically copied to the new backup file by AWS services within the cloud.

In the upshot, Synthetic Full Backup helps to substantially decrease upload volume from the local computer. According to our tests, it makes backup process up to 20 times faster (since copying files within the cloud is considerably faster than copying them from the local PC to the cloud). At the moment, the feature sticks to the AWS as it is one of the few systems that allow moving data blocks within the cloud storage. Now we’re working on implementing this feature for Azure Blob storage.

If you’re using a synthetic backup with Amazon S3 Standard-IA storage class, bear in mind one proviso regarding the pricing policy. When you initiate the second full backup, the principal part of those files will be copied within the cloud itself. And you will be charged accordingly — $0.01/GB.

How to Enable Synthetic Full Backup?

There are some restrictions on using the Synthetic Full Backup:

  • Amazon S3 or Wasabi must be the target cloud storage.
  • Encryption options must remain unchanged since the last full backup.
  • One or more full backups have to be made before you activate synthetic backup.

To enable the new feature, create a new image-based plan. Select the block-level checkbox when configuring a particular plan. Then select the Synthetic full backup check box.

Enabling Synthetic full backup option

Then, force a full backup from the Backup Plans tab to start using the Synthetic Full Backup feature. You can see it working in the Progress Bar.

Synthetic full backup - working in the progress bar

The synthetic image will display under the Backup Storage tab.

Synthetic image under the Backup Storage tab

CloudBerry Backup identifies the synthetic image as a full backup because there is no technical distinction between them so that you can operate them with CloudBerry Explorer, CloudBerry Drive or third-party apps.

Note that this feature only makes sense if the source partition is larger than 100MB.