Full, differential and incremental backup explained

There exist more than three backup methods. However, the three main include full, differential and incremental backups. The latter two are considered smart backup options mainly because they save back up time and storage space. This is not to mean they don’t have their downsides as well. Let’s explore how each works.

Full backup

A full backup is known as the starting point for all backups, containing all the data in folders and files that have been selected for backup. Since full backup stores all folders and files, regular full backups ensure simpler and faster restore operations. Other back up types make restore tasks unnecessarily longer.

Such backup is ideal every time you want to backup as it is self-contained and most comprehensive. Even though it is highly recommended, it consumes a lot of time thus discouraging many people from using it. Full backups should be restricted to either a weekly or monthly affair even though the ever-growing capacity and speed of backup media are making quick full backups more realistic.

It provides the best solution for data protection and given that you can set an automatic backup, it requires little supervision compared to the excellent results it offers. One single full backup provides the ability to restore all backup folders and files completely.

To be on the safe side, you should be fully aware of significant security issues that may arise during this process. Every full backup has an entire copy of data. If the backup data was to be accessed illegally, lost or stolen, the entire copy of your backup media could end up in the wrong hands. This is the reason you should ensure your backup program highly supports encryption to keep your data safe when backing it up.

This type of backup has two advantages: fastest restore of data and better storage management (complete backed-up data stored in a single file).

In terms of demerits, it is the slowest back up when compared to others. Also, it requires the highest storage space when compared to others.

As a general recommendation, even though full backup guarantees most protection, you should have a good backup strategy to ensure weekly and faster backups.

Differential backup

Differential backup copies and backs up all files that have changed since your last full backup. This means it shortens the restore time when compared to other backups. If frequently done, however, the file size may significantly increase to exceed the full baseline backup.

To understand this kind of backup, you can check out tools such as Ottomatik which has many programs that support differential backup and utilizes the data recorded in its catalogue files to determine files has changed since the previous backup.

The difference between incremental and differential backups is significant but confusing at times. While incremental backup includes all the modified files since your last fullback, differential or incremental backups, differential backup provides a middle ground just by backing up only data that have changed since your last full backup. That is where its name originates from; backing up every different thing since your last full backup.
When compared to an incremental backup, restoration of a differential backup process is faster because only two backup files are used; the latest differential and the most recent full back up files.

To use differential backup, you need a lot of time to execute the backups. The disadvantage is if you run several differential backups after you run a full backup, you’ll run a risk of including some files in every differential backup that haven’t recently been modified but were part of previous differential backups.

The main advantages include: faster restore speed as compared to an incremental backup, faster backup speed than a full backup and low storage space requirements than for total back up.

On the downside, it has a slower restore speed when compared to full back up. It has a more gradual backing up speed than an incremental backup and higher storage space requirements than an incremental backup as well.
As time goes by, the differential storage space can increase to equal or even become larger than that of a full backup. The following options can actuate creation of new full backups in such situations:

1. Run a full backup when the differential zip file size exceeds the percentage of a full backup.
2. Make a full backup when the size of differential zip exceeds 1Mbytes.

Incremental backup

This type of backup backs up all the files that have experienced change since your last full, incremental or differential backup. It has a reputation of taking the least time to back up data. On the downside, each increment is processed during a restore process thus resulting in a lengthy restore task.

Incremental backup offers a swifter method of backing up your data than running full backups repeatedly. During the backup, only files that have experienced a change since the last back up are backed up. Its name comes from here; each backup is an increment for the previous backup.

To execute backups, it uses a fraction of the time used for a full backup. This, however, comes at a price-increased restoration time. When performing a restoration from an incremental backup, you require the most recent full back up including all incremental files made since the previous full backup.

For instance, let us assume you executed a full back up on Monday and incremental backups on Wednesday, Thursday, and Friday. If you need to restore your backup on Saturday morning, you would require all the four backup container files- Monday’s full back up data plus the incremental backups for Wednesday, Thursday, and Friday. By comparison, if you were running a differential back up on Wednesday, Thursday, and Friday, then the restore on Saturday morning would have only needed Monday’s full backup plus Friday’s differential backup.

Advantages of incremental backup are:

1. Fastest backup type
2. Uses low storage space
3. Each backup increment can store different versions for files or folders

The disadvantages include:

1. Slow full restore compared to other backup types
2. Restoring the lasted version of individual files requires finding the increment containing the data.

Staff Writer