What is Full Backup?
Before getting to know incremental and differential backup, it is necessary for us to learn what "full backup" is. Full backup refers to creating a backup of all the valid data, whether it is new added or exists for a long time. Full backup does not depend on the file’s Archive Attribute to decide which file should be backed up. During a full backup, all existing marks will be cleaned and be marked as “backed up”, i.e. clear Archive Attribute. To create a full backup of selected files or applications means to create an identical duplication of these data at a particular time point. Therefore, with only one full backup, you can completely restore all data, which dramatically decrease the recovery time.
For instance, we’ll create a full system backup image using full backup software after installing an operating system. If the system is 12GB, all system files and applications will be backed up. We can easily perform a system restore using this full backup. This also applies to fully backing up a data partition, a file folder and the entire disk and so on.
However, full backup has a dead disadvantage as well. To keep the backup up to date, it is unavoidable to create more than one full backup. In that case, many identical data will be backed up again, which is a waste of time and storage. Luckily, the appearance of incremental backup makes it possible to figure out all these problems.
What is Incremental Backup?
Incremental backup means backing up all changed data based on last backup (full backup or incremental backup). During an incremental backup, all marked files and folders will be backed up. It will clear file’s Archive Attribute as well. Please note that the first incremental backup should be based on a full backup. Since incremental backup is created on the basis of last backup, there will be a mutual dependent relationship between them.
That is to say, with incremental backup software, each backup will create an image file of modified or new added files, and all of them are related together. The deletion of a previous image file will make all the subsequent image files invalid.
Here is an example of creating incremental backup. Suppose that D Drive has data as follows:
|File name||File size|
First, let's make a full backup of D Drive. And then there will be a 15GB image file: Full1.adi, which includes file1.txt and file2.txt.
Then, let's add two files, file3.txt and file4.txt to D Drive. Now D Drive will have the files as follows:
|File name||File size|
If we make an incremental backup of drive D for this time, then only the new added files, file3.txt and file4.txt will be backed up and generated as Incr1.adi. Compared to the image file backed up before, there is not any change for file1.txt and file2.txt so that they will not be backed up. If we add file5.txt and file6.txt, keep file1.txt to file4.txt unchanged, and run incremental backup again, only file5.txt and file6.txt will be backed up as Incr2.adi. Surely, if any file in file1-4.txt has changed, it will be backed up as well.
The greatest advantage of incremental backup is that there is no identical backup image created during the process, which is time-saving and storage-saving. However, the restoring of incremental backup might be troublesome. You need to prepare last full backup (Full1.adi) as well as all subsequent incremental backups (Incr1.adi and Incr2.adi) and restore them in the order of back up time point. This inadvertently increases the recovery time. If you lost any of them, the recovery will not succeed.
What is Differential Backup?
Differential backup will back up changed files based on the last full backup. This method also requires a full backup exists. All differential backups are based on the full backup, so they are relatively independent. During a differential backup, only marked files and folders will be backed up and the Archive Attribute will be not be cleaned, i.e. these files will not be marked as “backed up” after the differential backup. In terms of recovery, you just need last full backup and the latest differential backup. Here comes an example of creating differential backup with differential backup software.
Suppose that E Drive has the following data:
|File name||File size|
The first job is to create a full backup of file1.txt to generate Full1.adi.
Then add file2.txt and file3.txt to E drive. Run differential backup, and you’ll get Diff1.adi that contains file2.txt and file3.txt.
Then add file4.txt and file5.txt to E drive, run differential backup, you’ll get Diff2.adi that contains file2-5.txt.
The theory is the same. It will backup changed files based on last full backup. In that case, if you lost Diff1.adi file, you can still restore all files using Full1.adi and Diff2.adi. This method requires more time on backing up yet it costs less time in recovery.
Best Full/Incremental/Differential Backup Software – AOMEI Backupper
Software that supports full backup, incremental backup and differential backup can be called professional backup software. AOMEI Backupper Standard is such software that can create these three types of backup image perfectly. In addition, it is a freeware which is compatible with all PCs including Windows 10, 8.1, 8, 7, Vista and XP. This incremental and differential backup software allows you to incremental backup HDD to external hard drive with ease. Following are the detailed steps of backing up system drive incrementally.
1. Click Backup and then System Backup.
2. The system drive is selected by default. Click to choose a destination path.
3. Click Start Backup and a full backup of the system drive will be created.
4. After the backup finished, go to Home tab and you’ll find the system backup image you just created. Move over it and click Backup option in the middle. In the drop-down menu, select Incremental Backup.
5. In the pop-up window, you can write some comments for distinguishing. At last, click on Start Backup.
*This strategy is used to do incremental backup for one time. You can set auto incremental/differential backup with the help Schedule. (Scheduled differential backup is supported in Professional edition.) You can choose to “Add the schedule and start backup now” or “Only add the schedule” at the first Start Backup window.
For instance, if you set schedule backup at 6 p.m in daily mode, it will run full backup at 6 p.m of the first day and run incremental/differential backup at 6 p.m of the second day. It is suggested to run incremental backup in schedule. Otherwise, you need to repeat the last two steps manually every time.
*You can check all backups in the path: Home > Advanced > Locate Image.
*To incremental backup files like documents, photos, or music, please try File Backup.
*Backup Options: you can password protect images (supported by Professional edition), compress and split images here.
*Scheme: You can manage backup storage by deleting old backups automatically after upgrading to Professional edition.
With flexible backup method and powerful function of backup, restore and clone, AOMEI Backupper has been regarded as a rare and excellent software. With it, you can easily create incremental and differential backups for saving time and space. To learn more about the differences between incremental backup and differential backup in backup speed, storage and restore speed, please visit: incremental vs differential backup.