Full backup

The definition of a full backup is to make a complete copy of a business or organization’s data assets in their entirety. This process requires all files to be backed up into a single version. It is the best data protection option in terms of speed of recovery and simplicity because it creates a complete copy of the source data set. However, making a full backup demands copying a large volume of data, making this backup type a highly time-consuming process.

Each system will have slightly different requirements for how to create a full backup. However, the dataset should be copied in its entirety and stored in a separate location, away from the server. This way, should the server fail, the full backup will be immediately available for the restoration process.

Incremental, differential, and full backups are common techniques. Less frequently encountered types include forever-incremental, synthetic, and mirror backups.

Full backups: Full backups are complete copies of all configured data. This backup is best used periodically, although it is essential to have all data entirely backed up, because creating and implementing a full backup regularly consumes far more storage, time, network bandwidth, and other resources.

Incremental backups: Incremental backups save resources and time because they back up only the data that changed since the last backup of any kind. This consumes less time and storage space but makes restoration more difficult as it means restoring both the last incremental backup and the last full backup as well.

A full backup and a level 0 incremental backup are physically identical, with one difference: the level 0 backup can be used as the parent for a level 1 backup because it is saved in the RMAN repository, an online backup source of read/write data files, as an incremental backup.

Differential backups: Differential backups, also called cumulative incremental backups, also save resources and time because they backup only the data that changed since the last full backup — but in this case, where the incremental backup goes back to the last backup of any type, the differential backup restores data back to the last full backup only.

Comparing full, incremental and differential backups, the full backup is just like it sounds; the incremental backup covers just the most recent changes from the last backup of any type; and the differential backup goes back to the last full backup.

Backup systems perform full backups in many different ways. An incremental-forever approach performs just one full backup ever, followed by incremental backups. Block-level incremental-forever backups, a subset of this type, store the backup on the changed blocks rather than all files that have been created or modified since the last backup.

The synthetic full backup process can also reconstruct a full backup by copying data from existing backups. A synthetic full backup uses only the backup server and its storage; it consumes no resources of the system it is backing up.

Similar to the full backup, a mirror backup creates an exact copy of the source data set. However, while a classic full backup will track different versions of the files, in a mirror backup, only the latest data version is stored in the backup repository; the mirror backup copies only modified files. All individual backup files are stored separately, just as they are in the source, not in a single compressed/encrypted container file.

Mirror backups allow for quick, direct access to individual backup files without a formal restore operation. However, they also demand large amounts of storage, and present a high risk of data loss, data corruption, misuse, and unauthorized access. Furthermore, mirror backup files are actual mirrors, meaning they reflect what happens in the source files. Any adverse modifications to the source due to accident, human error, malware action, or sabotage may produce the same outcome in the mirror backup.

The advantages of a full backup are clear: it completely protects your system files and you don’t risk data loss. However, full backups take massive storage space and many labor hours to create. IT workload on the network interferes with routine infrastructure operations, and full backups consume extensive backup repository storage space. In fact, a full backup can take many times longer than other backup types.

In addition, each complete copy of your business’s data set is at risk of a breach. Any lost, stolen, or illegally accessed backup media contains a complete copy of organizational data, so full backups should be protected with encryption at a minimum — another additional expense and layer of complexity.

Incremental backup strategies are designed to address these flaws for different users. Advantages of incremental backup include lower costs, significantly lower storage space required, and faster backup times. On the other hand, the disadvantages of incremental backup include slower restoration time and added complexity in the restoration process.

Older backup systems perform occasional full backups to speed restore times, but many modern backup systems, especially cloud-based backup solutions, do not need to do this. Instead, they store all backup data in object format, and simultaneously restore all files and data regardless of how it was originally backed up.

Here is an example to explain full backup and incremental backup, and how they might work as part of an organizational backup strategy:

• On Monday, the team completes an initial full backup of all files on the designated hard drive.
• On Wednesday, the team completes an incremental backup of only the files that have changed since Monday — the last backup that was completed.
• On Friday, the team completes another incremental backup of just the files that have changed since Wednesday — the last backup that was completed. They repeat this again on Sunday.
• On Monday, the process begins again with another full backup to the designated hard drive.

(Most businesses medium-sized or larger opt for some form of daily backup such as a full system backup software; this is merely an example.)

By doing this, the team saves space in the drive. However, if they need to restore, it may cost them time. In the alternative, the team might adopt this plan:

• On Monday, the team completes an initial full backup of all files on the designated hard drive.
• On Wednesday, the team completes differential backup of all files that have changed since Monday — the last full backup that was completed.
• On Friday, the team completes another differential backup of all files that have changed since Monday — the last full backup that was completed. The backup from Wednesday is ignored because that is merely the latest differential backup. They repeat this again on Sunday, going back to the last full backup.
• On Monday the process begins again with another full backup to the designated hard drive.

This second strategy does require more space, but it is more of a compromise between the daily plan to run full backups and the reliance on incremental backups between spaced out full backups.

A combined strategy of full backups, differential backups, and incremental backups is also possible, and may work well, depending on the facts.

Druva’s flexible enterprise cloud backup system includes full and incremental backup tools — and much more. Its public cloud-native architecture allows for secure, simple, scalable enterprise cloud backup and restoration, even where bandwidth is scarce.

No hardware or software means there is no hassle in deployment. In fact, cloud incremental backup delivers a 50 percent lower TCO. Schedule your backups once and don’t think about them again until it’s time for a change.

Discover how Druva eliminates the cost and complexity of full backup on the website, and watch the video below for a demo of Druva’s cloud backup and disaster recovery in action.