Full, Incremental and Differential images and backups are saved to target folders specified in your backup definition file. Multiple backup sets can be created and you can choose between them when you run a Differential or Incremental backup.
For information on creating Incremental or Differential backups see here.
Specifying backup target folders
For disk images this is specified in the first page of the backup wizard:
Similarly, for file and folder backups, this is also on the first page of the backup wizard.
What is a backup set?
Backups are grouped into sets. A backup set contains a full backup and subsequent linked incremental and differential backups. You can see the links by looking at the default file name which is a unique backup set identifier, followed by a number pair:
Note: Windows Explorer does not show file name extensions (for example, mrimg) by default. To see file name extensions, click View in the Windows Explorer top menu and select file name extensions.
The above folder contents shows (marked in red) a single backup set {4F6F6CACA58B077D} which contains a full image and 4 increments. The end of the image file contains a number pair - xx-yy.mrimg.
xx is the increment number:
- 00 - Full image
- 01 - first incremental/differential
- 02 - Second incremental/differential
yy is the file number and is always sequential. 00, 01, 02, 03... . This is different to the increment number only if files are split. This can happen if files larger than 4GB are saved to a FAT32 file system or you are saving an image to multiple DVDs.
Note: The first file for a full image always ends with 00-00.mrimg.
The Image ID, file and increment numbers are also stored as data inside the files.
Renaming a file does not affect the integrity of the set, Macrium Reflects ability to append to the set, or restoration of the files.
How is a set chosen when an Incremental or Differential backup is run?
Each backup set is grouped by similar backup types. This means that a single set only consists of images of *exactly the same partitions or a File and Folder backup of exactly the same selection criteria.
*Note: A change in partition layout causes a new backup set to be created even if the drive letters are consistent. The partitions must have the same disk offset and length and must be from the same disk, i.e, the disk must have the same Disk ID. For example, if you run an incremental image of just the C drive and the target folder contains 4 image files:
- 6698CD700DF88DF4-00-00.mrimg Drives: C, D, E Created 1st Jan 2013
- 430D57E2CEEA8552-00-00.mrimg Drive: F Created 2st Dec 2012
- 1EB1112ABA7C3898-00-00.mrimg Drive: C: Created 1st Nov 2012
- D407A9E1BF98D822-00-00.mrimg Drive: C: Created 1st Oct 2012
The newly created image file is 1EB1112ABA7C3898-01-01.mrimg. This is because file 1EB1112ABA7C3898-00-00.mrimg is the most recent full image in the target folder containing exactly the same partitions as the current incremental image. The next incremental (or differential) image is 1EB1112ABA7C3898-02-02.mrimg and so on...
Note: If there was no existing backup set containing just the C drive then a new backup set (full) is created.
Doesn't this get confusing if multiple backup types are saved to the same folder?
Not if you use Restore in Macrium Reflect to view your images to mount and/or restore. Restore can be restricted to show only images that contain a particular drive and be sorted by date. So, if you want to restore the C drive to how it was last week than you can easily find it. In fact backup sets are an abstraction that you don't need to worry about when restoring data, they are only relevant to optimizing backup speed and storage space.
Note: If you want to organize your backup making them easier to find in Windows Explorer we recommend you save different backup types to different folders. for example:
- D:\Backups\Images of C
- D:\Backups\Images of D
- D:\Backups\Images of Disk 1
Additional Information
A differential backup only saves changes made since the last full backup, of the same type, found in the target folder for the backup.
An incremental backup only saves changes made since the last backup, of the same type, found in the target folder for the backup.