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. For instance, a backup of the operating system refers to back up all the data in system partition. If the system files of Windows 7 occupy 12GB, a full backup of this system partition will contain data of 12GB. Namely when making a full backup of a disk, all the data on the disk will be backed up. So does the full backup of a partition. The object of full backup can be system partition, data partition, a whole disk, etc.
Generally speaking, we will do a system full backup after installing operating system. After a period of time, we will add some data to system partition, and then we would like to do a system backup again. If we employ a full backup, it will cost more time than the last full backup. What's more, the compressed image file of the first full backup might occupy 8GB, and the image file of the second full backup might occupy another 8GB or more. In the two image files, there are many identical data. There is no need to back up these identical data for the second time. Only the new added data need to be backed up. Thus, it can not only reduce the time of backup, but also can reduce the storage space of the seconds image file.
Full backup mainly has two disadvantages. On one hand, it would cost more time. On the other hand, the image file of full backup requires more storage space. There isn't any way to remove the reduplicative data but to delete the image file of the last full backup. Luckily, the appearance of incremental backup makes it possible to figure out all these problems.
Incremental backup refers to back up the changed and new added data based on the first full backup or the last backup. Incremental backup will not back up the identical data based on the last backup. Incremental backup is on the basis of the last backup, so that there will be a mutual dependent relationship between them two. That is to say, each backup will create an image file, and all the image files are related together. The last image file of incremental backup is based on the previous image file. The deletion of a previous image file will make all the subsequent image files invalid.
Here is an example of 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: imagefile1.adb, which includes file1.txt and file2.txt.
Then, let's add 2 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 a full backup of Drive D during the second backup, all the 18GB data on Drive D will be backed up. Meanwhile it will generate an 18GB image file: imagefile2.adb. Now, file1.txt and file2.txt turn to be reduplicative data of the two full backup.
If we make an incremental backup of Drive D for the second time, then only the new added files-file3.txt and file4.txt will be backed up. 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. At last, the second incremental backup will generate an image 3GB file: image-inc.adb, which is based on imagefile1.adb. So if imagefile1.adb is lost, image-inc.adb will become invalid.
If we restore imagefile1.adb to Drive D, the restored D Drive will only consist of file1.txt and file2.txt. If we choose to restore imagefile2.adb or image-inc.adb to Drive D, all of the four files will be recovered.
Since incremental backup just deal with the changed, new added and deleted files, it will cost less time in restoring. Meanwhile, it omits the reduplicative data so that the storage space has been reduced, which makes up for the drawbacks of full backup.
Similar to incremental backup, differential backup is used to back up the changed data based on the last full backup. That is to say, it is based on full backup, not incremental backup. As for its advantage, it can help to improve backup efficiency and reduce storage disk space required by the image file. It is another form of incremental backup. Here comes an example of differential backup.
Suppose that E Drive has the following data:
|File name||File size|
The first full backup of Drive E will back up file1.txt, and then generate an image file: image1.adb.
Then, add file2.txt to Drive E, and then make an incremental backup to generate an image file: image2.adb.
Then, add file3.txt to Drive E, and then make an incremental backup to generate an image file: image3.adb.
Then, add file4.txt to Drive E, and then make an incremental backup to generate an image file: image4.adb.
At this moment, there are four image files all together. Image4.adb is based on image3.adb; image3.adb is based on image2.adb; image2.adb is based on image1.adb. In conclusion, incremental backup is always based on the image file of the last backup.
At this time, if we do a differential backup and generate an image file: image-diff.adb, these three files: file2.txt, file3.txt and file4.txt will be backed up together, excluding file1.txt. Because differential backup is just based on full backup, and the file1.txt has been backed up in the first full backup, so it will not be backed up again. At this time, image-diff.adb is just on the basis of image1.adb, and has no connection with the image files: image2.adb, image3.adb, and image4.adb.
During the operation of restore, if we restore image2.adb to Drive E, the restored Drive E will include only two files: file1.txt and file2.txt, excluding file3.txt or file4.txt. If we restore image4.adb or image-diff.adb to Drive E, all the four files: file1.txt, file2.txt, file3.txt and file4.txt will all be restored back.
Software that can complete incremental and differential backup can be called professional software. AOMEI Backupper is such as software, which can complete full backup, incremental backup and differential backup perfectly. In addition, it is a freeware, which supports all PCs. It can back up and restore system and other partition as well. The following is the detailed operating steps of backing up a partition.
First, select "Partition Backup" under the "Backup" tab. (Note: Also you can create a full backup of disks or system partitions by selecting "Disk/System Backup" here.)
Second, make a full backup of Drive D, and set Drive F as the destination path. Then, click "Start Backup".
Third, when the operation has been completed, click "Finish" to exit the interface.
Then, the process of full backup is completed. Under the "Home" tab, you can preview all the backups. Supposing you have added some files to Drive D, making an incremental backup for the newly added files. Please just follow the steps as follows. Click "Incremental Backup" under the "Backup" item. Then, the program will directly go to the execution page, and then the operations will be carried out automatically.
After the operation has been completed, you can preview all the versions of this backup task through Home-> Advanced-> Properties.
Then, all the image files of this backup will be listed under the "Versions" tab.
As for the operations of differential backup, it is similar to that of incremental backup.
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. You can download it by clicking the following link.