What is Incremental Backup in Backup and Recovery Management


Technology has brought revolution in the life of a common man along with the transformation of corporate practices. But this technological revolution has posed a lot of threats to data security and integrity. With more exposure to digitalization, there has been a lot of incidents which have resulted in the incidents of data loss and theft.

This does not mean that technology usage should be abandoned. Instead, there is a need to look for ways to ensure data security. Data backup and recovery management is an excellent way to counter such menaces of data loss and theft. Out of many backup methods, such as incremental and differential backups, incremental backup is the storage efficient backup approach. Owing to the less usage of resources, most of the cloud storage backups use incremental backups.

Working Principle

In incremental backup, only that data is copied which has been either created or modified since the last backup exercise. By backing up only modified or newly created files, incremental backups save storage space and so does the duration of the restoration process.

At first, incremental backup scenarios need a full backup of the data. Afterward, subsequent increments of the backup will be made over a period of the time. For instance, if an initial full backup is made on Monday, then the backup software on Tuesday will backup the files which have been either created or modified since Monday. Subsequently, Wednesday’s incremental will back up the files which have been changed since Tuesday and so on, until the full backup is performed again on Monday.

For the up-to-date restoration of the data, it is important that each incremental backup must be performed since the last full backup. Although the restoration process will take some time to fully restore the data and prepare a subsequent full backup, still this time will be much less than what will be incurred with the full restoration of different types of backup.

Types of Incremental Backups

There are many scenarios and types by which incremental backup can be processed. Following are the list of different types of incremental backups:

Synthetic Full Backup

This type of incremental backup is usually done by recording the previous full backup and subsequent incremental backups. This is much different from the full backup where all files of the primary storage will first be read and then they will be copied.

This type of backups usually makes the backup process less time consuming and more efficient. Because sometimes volume of the data is so huge that full backups can not be prepared without business disruption.

In such scenarios, synthetic full backups do not only offer data security, but they also reward users with time efficiency.

File-level Incremental Backup

This type of incremental backup is ideal for the smaller datasets. Here, data is usually backed up on the simple and granular scale. Whenever the system identifies a change or modification in the directory, it sends that incremental to the repository. This repository then copies and backs up that file.

Block-level Incremental Backup

It is the most common form of incremental backup where written storage blocks are backed up rather than backing up the full copy of files and folders. These blocks will have either a modified or newly created file/data.

This type is more effective and accurate as compared to the file-level incremental backup. Because rather than backing up the entire file, the blocks that are changed are only backed up. Data access using this approach is being used by Storage Area Networks (SAN) and many other storage systems. So, it can be said that this type of incremental backup provides faster backups.

Byte-level Incremental Backup

Byte-level incremental backup is further vigorous than the block-level incremental backup. In this type of incremental backups, the data is constantly being monitored for any change in the individual bytes. In case of any change, then on incremental basis that modified byte is backed up.

These types of backup deals with a small amount of data. Therefore, it is just to say that this type yields the smallest possible backups.

Incremental Forever Backup

Incremental forever backup is also known as progressive incremental backup. This type of incremental backup is designed to ease the backup process for the disk-based backup systems.

Once an initial copy of the data is made, the software will just back up the new or modified data. There is no need to create the periodic full backups as the backup will be disk-based. Furthermore, it is quite easy to apply incremental changes to the disk-based copy of the file.

Enhanced Incremental Backup

Some of the backup vendors introduced a backup feature to which they refer as “enhanced incremental backup”. This feature adds another oversight layer with the purpose of making backups more comprehensive and up-to-date.

In addition to the identification and backup of modified or new files, the enhanced feature makes sure that the backup process should be able to recognize some other features too. These additive features include identification if any file that has been either removed or moved out of the directory.

Reverse Incremental Backup

This type of incremental backup is more or less the same as that of the synthetic full backup. Reverse incremental backup first creates a full backup, as in any other type of incremental backup. Once first incremental is created, this incremental will then be applied to the initially obtained full backup, so as to create a new full backup. It must be noted that this full backup will be the copy of the former full backup and will thus be obtained without altering the former full backup. Afterward, the next incremental will be obtained by capturing the changes against the new full backup. In this way, without getting into the process of each incremental, full backup copy will always be available. Furthermore, if an event of virus contamination has been encountered, this process also eases down the process of reverting back to the earlier copy of the full backup.

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