The backup dilemma

In principle, backups always follow the same procedure:

1. First, a full backup is created and saved.
2. Over a certain period of time, the differences to the first full backup are recorded at regular intervals and saved as incrementals.
3. A full backup is then created again and saved as the new start for the next incrementals.
4. Once the desired backup period has been reached, the oldest full backups and the corresponding incrementals are deleted (rotation).
5. To protect backups separately from the backup software using immutability, the storage system creates snapshots at regular intervals, which are also written and deleted according to the rotation principle.

The intervals between the incrementals and between the individual full backups as well as the backup period are individual for each data class and application and largely determine the technology used.

As you can see, a lot of duplicate data is created during this process.

The more full backups are written and the longer the backup period, the greater the storage requirements, which can quickly amount to 10-20 times the original amount of data to be backed up.

As a lot of data is transferred and stored with every full backup, such conventional backups can also take a very long time. The backups often threaten to exceed the available backup window.

Fast Clone & RefLink:

Synthetic Full

To prevent this duplicate data as far as possible, Veeam Backup & Recovery can reference and link data blocks once they have been written (RefLink). A "Synthetic Full" created in this way consists only of references to the data blocks already present on the storage system. Veeam calls the process of creating such a "link collection" Fast Clone.

This is much faster and of course uses much less storage space than writing a new "real" full backup each time.

The consequences: Significantly less storage space is used and the time required for a full backup is dramatically reduced.

Many restore points can be created in the secondary target over a long backup period without storage requirements and backup time getting out of hand.

Fast Clone & RefLink:

Forever Incremental

In the primary target, where the data that is immediately necessary for operations is backed up, several full backups are often not used - on the one hand because data that is older is stored in the secondary anyway, and on the other hand because the speed of the restore is important here and expensive flash media is therefore used.

Here too, Fast Clone can save considerable storage space and time.

Since a new, complete set must be available before a full backup set can be removed, at least two full sets of storage space are always required. Veeam has also come up with a solution for this: Forever Incremental.

After the first full backup, only incrementals are written. At the end of the backup period, the first incremental is then merged with the full backup using Fast Clone and then deleted. This is repeated after each backup interval so that only one full backup and the set number of incrementals are ever present on the storage system.