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The benefits of differential and incremental backup

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The benefits of differential and incremental backup



In the Free Edition of Macrium Reflect, you are only able to make full images of your disks and partitions. In creating a full image, the entire contents of the imaged file system are stored in the image file. Although this is a reliable way of backing up your PC, repeating the process is slow and subsequent images can fill your target media very quickly. However, in the paid versions of Macrium Reflect, it is possible to create differential and incremental images which are both quicker to execute than full images and create much smaller image files.

Differential Images
In order to create a differential image, a full image must first be created. The differential then stores only the changes that have been made to the imaged file system since the last full image. It is possible to take subsequent differentials, but only one differential and the full are required in order to fully restore the system. However, the longer the time between the full and the differential, the larger the differential image file will be and the longer it will take to create.

Advantages
  • Differential images created after the initial full Image are very quick because only file system changes since the full backup are saved.
  • The amount of disk space used by differential images is significantly less than that of full images
  • Only two image files are required to restore the system

Disadvantages
  • As the time since the last full image was taken increases, the size of the differential will grow as will the time it takes to create the differential image. In order to reduce this time, it is necessary to perform a full image occasionally to reduce the size of the subsequent differential images.
Incremental Images
Incremental images are similar to differential images in that they require a full backup to be made first. However, the main difference is that they only store file system changes since the last image, either full or incremental. The resultant backup set will therefore consist of a full image and a number of incremental images which must all be present in order to restore the system correctly.

Advantages
  • Incremental images have the same advantages as differential images, but since they only store the changes that were made since the last full or incremental. They are always small and very quick to make, especially if done frequently.
Disadvantages
  • The only disadvantage to using incremental images is that all files must be present in the image set. If any intermediate incremental images are missing, it will not be possible to restore the system to the latest backup.

Managing Differential and Incremental images in Macrium Reflect
It may appear to be quite an onerous task to maintain the backup sets. With this in mind, Macrium Reflect takes care of all the hard work for you. It is possible to schedule incremental or differential backups automatically. When restoring an image, you select which image you wish to restore and Macrium Reflect automatically select the required files in the image set as part of the restore process. The same is true for exploring an image. If you choose to explore an incremental image in an explorer window, Macrium Reflect will reconstruct all the files that have been backed up to that time.

Macrium Reflect also includes functionality that allows you to automatically delete image sets that have expired. For example, if you take a full image  every month and then incremental images every day, you can configure Reflect to keep two full image sets (the equivalent of two months of backups) and delete any older files. As a result of this, your backup media will not end up becoming full of obsolete image files.


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Last Modified:16 Dec 2013

Last Modified By: Administrator

Type: Info

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