Full, incremental and differential backups
Acronis True Image Home 2011 offers you three backup methods:
1) Full: contains all of the data at the moment of the backup creation. It forms a base for further incremental or differential backups. It can also be used as a standalone backup.
2) Incremental: Only those files will be included which have been changed since the LAST backup.
3) Differential: Only those files will be included which have been changed since the last FULL backup.
We suggest you to choose one of the following three approaches of using the backup methods:
“Full” – A standalone full backup might be an optimal solution if you often roll back the system to its initial state or if you do not like to manage multiple files.
“Incremental” – These are most useful when you need frequent backups and the ability to roll back to a specific point in time. Having created a full backup once, if you then create an incremental backup each day of a month, you will get the same result as if you created full backups every day. Incremental images are considerably smaller than full or differential images.
Such a backup scenario may consist of a weekly full system backup with intermediate, daily backups that cover data that was changed since the LAST backup.
This scenario, while requiring less storage space and time for the daily backups, will require more work on your part to provide recovery after a system crash. In the event of a Thursday crash, you would have to recover the last FULL backup followed by the Monday, Tuesday and Wednesday incremental backups.
“Differential” – is an intermediate between the first two approaches. It is also good when the conditions are intermediate. Each differential backup includes all the files changed since the last full backup. It takes less time and space than “Full”, but more than “Incremental”. The good thing is that recovering is simpler than for (2) – you’ll have to recover the last full backup and the last differential backup.
Examples and recommendations
To choose a desired backup method, you need to configure a custom backup scheme. For more information see Custom scheme.
You can choose any approach for each of your backup projects according to their size and frequency of file modifications. For example if almost all the included files appear changed before an incremental backup starts, the incremental backup will be almost of the same size as a full backup would be. If so, let it be “Full” to simplify the recovery.
A “differential” backup scenario uses the same weekly full system backup with the backup of files that have changed since the last full backup on a daily basis.
While this scheme takes up progressively more storage space as each new day of the week passes, a recovery would only involve two backups – the last FULL backup followed by the previous day’s differential backup. Many users prefer this method as it simplifies recovery and most backups are done overnight.
In these examples, the only differences in the two backup scenarios are:
Incremental backups require less storage space while differential backups require more.
Incremental backups require all of the backups used for that week in order to do a complete recovery, while the differential backup only requires a maximum of two backups at any given time.
An incremental or differential backup created after a disk is defragmented might be considerably larger than usual. This is because the defragmentation program changes file locations on the disk and the backups reflect these changes. Therefore, it is recommended that you re-create a full backup after disk defragmentation.
If you lose an incremental backup version or it becomes corrupted, all later incremental backup versions will be unusable.
Deleting backups and backup versions
You may want to delete backups and backup versions you no longer need. Acronis True Image Home 2011 stores information on the backups in a metadata information database.
Therefore, deleting unneeded backup files by using Windows Explorer will not delete information about these backups from the database, and Acronis True Image Home 2011 will consider that they still exist.
This will result in errors when the program tries to perform operations on the backups that no longer exist. So you must only remove obsolete backups and backup versions by using the tools provided by Acronis True Image Home 2011.
To delete an entire backup:
On the main screen, find the corresponding backup box, click Operations, and then click Delete backup.
When you delete an entire backup, all its versions will be deleted as well.
To delete a specific backup version:
- On the main screen, find the corresponding backup box, click Explore and recover or Explore all versions.
- In Backup explorer, right-click the version you want to delete, and then click Delete version.
When you delete a backup version, please remember that this version may have dependent versions. In this case the dependent versions will be deleted as well, because data recovery from such versions becomes impossible.
- If you delete a full backup version – the program will also delete all subsequent incremental and differential versions till the next full version.
- If you delete an incremental backup version or a differential backup version – the program will also delete all subsequent incremental versions till the next full or differential version.