What is a full backup?

A full backup is a backup of every file on a file system, whether that file has changed or not.

The alternatives to a full backup are incremental backup and differential backup.

A full backup takes longer to accomplish and requires the most storage space on the backup media, but it also provides the quickest restore times.

A full backup should be performed weekly or monthly on production systems, along with daily differential backup.

A full backup should also be performed before any major planned changes to a system.

What is an incremental backup?

 

A incremental backup is a backup of every file on a filesystem which has changed since the last backup.

The alternatives to an incremental backup are differential backup and full backup.

An incremental backup is the fastest backup and requires the least storage space on the backup media. However, incremental backups also require the longest time and the most tapes to restore.

Incremental backups should be used only in environments where backup time or backup storage media are extremely constrained. For most environments, a weekly full backup and a daily differential backup represent a better plan.

If you perform a full backup on Sunday along with incremental backups every night and the system crashes on Thursday, you will need to restore the full backup from Sunday along with the incremental backups from Monday, Tuesday, and Wednesday.

In contrast, if you perform a full backup on Sunday and a differential every night, when the system crashes on Thursday you will only need to restore the full backup from Sunday and the differential backup from Wednesday.

What is a differential backup?

A differential backup is a backup of every file on a file system which has changed since the last full backup.

The alternatives to a differential backup are incremental backup and full backup.

A differential backup can be an optimal middle-ground between a full backup and an incremental backup.

A differential backup is not as fast as an incremental backup, but it is faster than a full backup. A differential backup requires more storage space than an incremental backup, but less than a full backup.

A differential backup requires more time to restore than a full backup, but not as much time to restore as an incremental backup.

If you perform a full backup on Sunday and a differential every night, and the system crashes on Thursday, you will only need to restore the full backup from Sunday and the differential backup from Wednesday.

In contrast, if you perform a full backup on Sunday and incremental backups every night, when the system crashes on Thursday, you will need to restore the full backup from Sunday along with the incremental backups from Monday, Tuesday, and Wednesday.

A differential backup should be performed daily on production systems.