Target Skills:

Ability to describe the three basic backup methods.

 
 
 
     

Backup Methods

There are three basic backup methods:  full, differential and incremental.
 

Full

In a full backup, all the data on a given directory or volume is backed up.
Advantages
 A complete copy of all the data.
Disadvantages
Backups take longer. 
Requires more storage media.

Differential

In a differential backup, only data that has changed from the last full backup is saved.  For example, a full backup is made on Sunday.  Monday’s backup includes all the changes for Monday.  Tuesday’s backup includes all the changes for Monday and Tuesday.  The differential backup sets are dependent on the last full backup as a point of reference.  Thus, if it is necessary to restore to Tuesday’s backup, only Sunday’s and Tuesday’s backups are restored.
Advantages
Much faster than full backup. 
Less storage required. 
Easy to restore.
Disadvantages
Takes more storage space and is slower to backup than incremental.

Incremental

In an incremental backup, only data that has changed from the last full or incremental backup is saved.  For example, a full backup is made on Sunday.  Monday’s backup includes all the changes for Monday.  Tuesday’s backup includes all the changes for Tuesday. Wednesday’s backup includes all the changes for Wednesday.  The incremental backup sets are dependent on the last incremental backup as a point of reference.  If it is necessary to restore to Wednesday’s backup, Sunday’s full backup is restored, then Monday’s, Tuesday’s and Wednesday's incremental backups.
Advantages
Takes least amount of storage. 
Fastest to backup.
Disadvantages
Restore is much more difficult and time consuming than differential.
     

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