Question #3
What different types of backups can be done?
a. Full, differential, incremental
b. Full, minor, instant
c. Half, major, timed
d. Full, half, continuous
Were you correct? The correct answer is:
a. Full, differential, incremental
Learn more:
As a backup practice, both incremental and differential backups accomplish the same thing: They allow you to reduce the resources needed to backup data. But how they accomplish this task is different.
If archive bits are cleared after each backup, this is called an "incremental" backup. If the archive bits are cleared only after a full backup, then this is a "differential" backup.
An incremental backup clears the archive bits each time data is backed up. This means that each backup will be small. To perform a restore, a copy of the last full backup and each incremental will have to be restored to get all files to their last known state. In most cases, a full backup will be performed weekly while an incremental backup is performed daily.
A differential backup clears archive bits only after a full backup. This means that daily backups get gradually larger, but restore is easier. A full restore only requires the last full backup and the last differential.
Incremental backup allows for a more granular restore, but differential backups are typically easier to restore.
Related articles:
- Backup
basics: Three backup plans -- ten tape backup
- Which
product, incremental or differential? - Part I
- Which
product, incremental or differential? - Part II
This was first published in April 2004
Storage Management Strategies for the CIO