home > Internet > Incremental backup. Full, incremental, differential - about backup methods

Incremental backup. Full, incremental, differential - about backup methods

What is an incremental backup?

Incremental backup.
Copy only new and changed files.

incremental backup (incremental backup) is a type of differential backup, when not all source files are copied, but only new and modified from the moment the previous copy was created - full or incremental. This significantly saves disk space and greatly speeds up the backup process.

The name of this type of backup comes from the English word incremental backup- additional. In Russian it is called Additional. This type Reserve copy is the most common, but, like all methods, it also has its pros and cons.

This type of backup is perfect for backing up large amounts of source data, 50 gigabytes or more. The speed of creating backups will be quite high, and the size of each incremental copy can be only 100-200 megabytes.

Pros :

Quick Creation backup
Small backup footprint (saving disk space)

Minuses :

Complexity of setup (compared to a full copy of Full Backup)
Difficulty in restoring files (compared to a full copy)

Conclusion: Create incremental backups if the amount of source data is large and time for copying files and saving disk space matters to you. The optimal frequency of creating an Incremental backup is 1 time per hour, if source files change frequently and 1-2 times a day if the files are rarely edited.

How to make an incremental backup with Exiland Backup

Exiland Backup is a simple utility for backing up and synchronizing folders over the network, FTP, between PCs and servers. Supports all types of file backups.

This universal program well suited for backing up file 1C, sites on Wordpress and other CMS, copying site files from an FTP server to a local PC.

To get started, download the free or demo version of the program on the official website.

After launch, in the main window of the program, on the top of the panel, click the button for creating a new task, specify the name of the task, for example, "My Documents" and click "Next". Now, as shown in the screenshot below, select the copy type "Incremental".

Screenshot of the program. Select the type of copy.

Below there is an option to limit the number of full copies so that the oldest backups were automatically deleted before creating a new full copy. This setting saves disk space (not available in Free versions). You can also limit the number of incremental copies between full. When this limit is reached, another full copy will be created.

When choosing a backup naming template, you can add a string such as "(incremental)" for incremental backups to visually distinguish them from full backups.

When the task is created, you do not have to wait for the start time - you can start the task manually by clicking on the "Run" button located on the top panel.

Michael, software developer

Other types of copying.

Saves only data that has changed since the previous full backup. This saves time and storage space for backups. Handy Backup supports differential copying of any data.

Principle of differential backup

Differential backup first creates a complete copy of the input data set once. Each subsequent copy saves only the data that has changed since the full copy.

Benefits of Differential Copy

A differential copy usually takes up much less space than a full copy. So, if out of 2000 files in the data set, only 10 have changed since the full copy, then differential copy will save new versions of only these 10 files.

With differential copying, not all data from the set is subject to processing, saving working time and computer resources is achieved. The calculations required to determine the changes take negligible time compared to writing the data.

Reduce costs and costs in data recovery

Differential backup allows you to restore data faster than full backup, due to the smaller amount of information copied, and faster than incremental backup, since there is no need to keep track of all changes in the data.

Handy Backup as a differential backup program

In Handy Backup, differential backup is implemented for any type of data. It is especially recommended to use this technology when regularly copying large, frequently changed data sets, such as SQL databases.

How to apply differential backup in Handy Backup?

Create a new backup task, specify data sources and storage for backups. In Step 4, select the type of copy - "Differential".

Advice: differential copying is most effective when combined with scheduled task execution. Specify a schedule for the task in Step 6 - Handy Backup will perform automatic differential backups at the specified time.

Restoring data from a differential copy

Restoring data from a differential backup requires only two sets of data: the last full copy of the data and the last differential copy.

For comparison: when restoring data from an incremental backup, you need all incremental copies of the data for the period of time being restored.

Try it right now!

Download the most latest version Handy Backup and try your own differential backup of any of your data during the 30-day free trial period. Personal experience is the best adviser!

Full, incremental and differential backups

Acronis Backup & Recovery 11 provides the ability to use popular backup schemes such as "grandfather-father-son" and "Tower of Hanoi", as well as create your own backup schemes. All backup schemes are based on full, incremental and differential backup methods. The term "scheme" really refers to the algorithm for applying these methods in combination with the algorithm for cleaning the archive.

Comparing backup methods with each other does not make sense, since they work together in the scheme. Each method should fulfill its own role according to its benefits. A good backup scheme allows you to use the advantages of all methods, while reducing the impact of their disadvantages. For example, weekly differential backups make it easier to clean up the archive because they are easy to delete along with a set of weekly incremental daily incremental backups that depend on them.

A backup using the full, incremental, or differential backup methods creates a backup of the appropriate type.

Full backup

A full backup stores all the data you choose to back up. A full backup is the foundation of any archive and forms the basis for incremental and differential backups. The archive may contain several full backups or consist of only them. A full backup is self-contained: you don't need access to any other backup to restore data from it.

It is widely known that a full backup is the slowest to create and the fastest to restore. With Acronis technologies, restoring from an incremental backup can be as fast as from a full backup.

Full backup is most useful in the following case:

you need to restore the system to its original state,
the original state rarely changes, so there is no need for regular backups.

Examples: an Internet cafe, a school or a university lab where the administrator often undoes changes made by students or guests, but rarely updates the base backup (only after installing software updates). The backup time is not critical in this case, and the recovery time will be minimal if you restore the system from a full backup. For added security, an administrator can have multiple full backups.

incremental backup

An incremental backup stores data changes relative to to the last backup. To restore data from an incremental backup, you need access to other backups from the same archive.

Incremental backup is most useful in the following case:

you want to restore one of several saved states,

It is widely known that incremental backups are less reliable than full ones, because if one copy in the "chain" is damaged, the following copies can no longer be used. However, keeping multiple full backups is not the best option if you need to have multiple previous versions of your data, because the reliability of an archive that is too large is even more questionable.

Example: backing up the transaction log of a database.

Differential backup

A differential backup stores data changes relative to last full backup. To restore data from a differential backup, you need access to the corresponding full backup. Differential backup is most useful in the following case:

only the last state of the data needs to be saved,
data changes are relatively small compared to the total size of the data.

It is generally believed that "differential backups take longer to create and recover faster, while incremental backups take longer to create and slower to restore." In reality, there is no physical difference between an incremental backup attached to a full backup and a differential backup attached to the same full backup at the same point in time. The above difference implies that a differential backup is created after (or instead of) multiple incremental backups.

An incremental or differential backup created after a disk defragmentation can be much larger than usual because the defragmentation process changes the location of the files on the disk and the backup reflects those changes. After defragmenting the disk, it is recommended to create a full backup again.

AT following table generally recognized advantages and disadvantages of each type of backup are indicated. In reality, these parameters depend on many factors, such as the amount, speed and nature of data changes, their nature, physical characteristics of devices, backup and recovery settings. The best teacher in choosing the best backup scheme is experience.

Parameter	Full backup	Differential backup	incremental backup
Disk space	Maximum		Minimum
Time of creation	Maximum		Minimum
Recovery time	Minimum		Maximum

But somehow I missed the theoretical part. In the comments, you periodically ask me about backup methods - full, incremental and differential. What is their difference, what is better to choose, etc. In this article, in fact, we will deal in detail with all these issues.

And I suggest understanding backup methods using the program as an example. So friends, when we AOMEI program Backupper create a backup a copy of Windows, a whole disk, separate partitions or separate folders with data, in the future, after creating a backup, we can use some software features for it. Among them is the creation of new copies based on the specified backup conditions with the choice of a backup mechanism:

Full copy;
incremental copy;
differential copy.

What are these mechanisms?

Full backup

Full is a backup in which the snapshot operating system, disk, partition, or individual folders contains all backed up data. Such snapshots created within the same backup task are independent of each other, damage to one of them will not affect other snapshots in any way. This is the most reliable method backup, but at the same time, the most expensive in terms of disk space resources. For example, image working Windows without any special bulky programs and games, it will weigh about 20 GB. If you do not get rid of the old ones as you create new backups, the storage disk will simply be clogged with them to the eyeballs. Two other backup mechanisms are designed to solve this problem.

Incremental backup

Incremental is such a backup in which a full copy is created once at the beginning, and all subsequent copies created within the same task do not contain all the data, but only the changes that have occurred - which files have been deleted and which have been added. The first incremental copy contains the difference in data between itself and the full copy. And the second incremental copy contains the difference between itself and the first incremental copy. The third is between herself and the second. And so on. Each new incremental copy depends on its predecessor and cannot be used for the restore process without such a predecessor. And, of course, without a full primary copy. Each of the backup copies of the task - whether full or incremental - is a restore point. And we can always choose the date or time to which we want to roll back the system or data.

Deleting an incremental copy (or damaging it with viruses) will not result in the inoperability of previous incremental copies and the primary full one. But the next ones will be. We will no longer be able to roll back to points after a remote incremental copy. In this regard, of course, the incremental copy method is vulnerable, but its strong point is to provide rollback to different state points with minimal disk space. After all, with minor changes, each new copy will weigh a couple of MB of difference between it and its predecessor. Here is how, for example, a partition backup in the screenshot below. The weight of 3.57 GB marked with a purple marker is the weight of the full primary copy, and the weight of 9.12 MB and 20.01 MB marked with a yellow marker is the weight of incremental copies.

Another drawback of incremental backups is the longer recovery process than from full and differential backups.

Differential backup

Differential is a backup in which a full copy is created once at the beginning, and all subsequent copies created within the same task do not contain all the data, but only the changes that have occurred since the creation of the primary full copy. The key point here is from the moment the complete copy is created. Whereas with incremental copying, the second incremental copy of the chain is the difference between it and the first copy, with differential copying, both the first, second, third, and fourth, and all subsequent differential copies will depend only on the full copy. But not dependent on each other. Removing or corrupting any of the differential copies will not affect the other copies - neither those created before the deleted (corrupted) one, nor those after it.

Differential backups are also recovery points.

The need for the differential copy to compare itself each time with the full primary copy, consequently, entails the use of more disk space. In the screenshot below, the purple marker marks the size of the full backup and the yellow marker marks the size of the differential backups. The size of the latter in the region of 450 MB indicates that there have been few changes between them, however, each such change since the creation of the full copy was recorded in a separate order. And in a separate order absorbs disk space.

Which method is better to choose

Which of the backup methods - full, incremental or differential - should you choose for common household needs? Full is the most reliable, but it is not always advisable to create a full copy every time. In cramped disk space conditions, a branching system of rollback points cannot be particularly configured. Incremental will save disk space, but if a virus damages an intermediate copy or, for example, someone close to it accidentally deletes it, we will not be able to roll back to fresh backups. The best option– differential backup. It can be performed periodically manually or configured for auto start in the scheduler of the backup program.

But there is another caveat, my friends. Some advanced backup programs can offer not only one or another method of creating a backup, but also its application in certain conditions. For example, AOMEI Backupper has 5 backup schemes. Schemas can be enabled immediately when creating a primary backup.

And you can connect later.

When configuring schemes, you need to check the box "Enable disk management". And in the drop-down list below we will see the top five flexible solutions from AOMEI Backupper.

What are flexible solutions? It:

"Full copy" - a scheme using the full backup method, in which, upon reaching the designated number of copies, the old ones will be automatically deleted;

"Incremental copy" - scheme with incremental backup. Upon reaching the designated number of copies, the chain of previous copies - full and dependent incremental ones - is deleted, giving way to new chains;

"Differential copy" - a scheme with the creation of full and differential copies. Upon reaching their limit number, the old ones are deleted, and all this happens taking into account the binding of differential copies to their full ones;

An incremental ("incremental") backup only copies files that have changed since the last full or incremental backup. A subsequent incremental backup only adds files that have changed since the previous one. On average, incremental backups take less time because fewer files are backed up. However, the data restore process takes longer because the data from the last full backup must be restored, plus the data from all subsequent incremental backups. In this case, unlike differential copying, changed or new files do not replace the old ones, but are added to the media independently.

Cloning

Cloning allows you to copy an entire partition or media (device) with all files and directories to another partition or media. If the partition is bootable, then the cloned partition will also be bootable.

Image backup

Image - exact copy the entire partition or media (device) stored in a single file.

Real-time backup

Real-time backup allows you to create copies of files, directories and volumes without interrupting your work, without restarting your computer.

rotation schemes.

Changing the working set of media during copying is called media rotation. For backup, a very important issue is the choice of a suitable media rotation scheme (for example, magnetic tapes).

One time copy the simplest circuit, which does not involve media rotation. All operations are carried out manually. Before copying, the administrator sets the backup start time, lists file systems or directories to be copied. This information can be stored in a database so that it can be used again. With one-time copying, full copying is most often used.

Simple rotation Simple rotation means that a set of tapes is used cyclically. For example, a rotation cycle can be a week, then a separate media is allocated for a specific working day of the week. The disadvantage of this scheme is that it is not very suitable for archiving, since the number of media in the archive is growing rapidly. In addition, incremental/differential writes are carried out on the same media, which leads to their significant wear and, as a result, increases the likelihood of failure.

"Grandfather, father, son" This scheme has a hierarchical structure and involves the use of a set of three sets of media. Once a week, a complete copy of the computer's disks is made ( "father"), while incremental (or differential) backups are performed daily ( "son"). Additionally, once a month, another full backup is performed ( "grandfather"). The composition of the daily and weekly set is constant. Thus, compared to a simple rotation, the archive contains only monthly copies plus the latest weekly and daily copies. The disadvantage of this scheme is that only the data available at the end of the month, as well as the wear and tear of the media, are included in the archive.

The "Tower of Hanoi" scheme is designed to address some of the shortcomings of the simple rotation scheme and the "Grandfather, Father, Son" rotation scheme. The scheme is based on the use of several sets of media. Each set is designed for weekly copying, as in the simple rotation scheme, but without the withdrawal of full copies. In other words, a separate set includes media with a full weekly copy and media with daily incremental (differential) copies. A specific problem with the Tower of Hanoi scheme is its higher complexity than other schemes.

"10 sets" This scheme is designed for ten sets of media. The period of forty weeks is divided into ten cycles. During the cycle, each set is assigned one day of the week. After a four-week cycle, the set number shifts by one day. In other words, if in the first cycle set number 1 was responsible for Monday, and set number 2 was responsible for Tuesday, then in the second cycle set number 2 is responsible for Monday, and set number 3 is responsible for Tuesday. Such a scheme allows you to evenly distribute the load, and therefore, wear between all media.

28.05.2021

Internet

The most interesting: