Differential vs Incremental backups

Deus Ex Machina

Hi everyone,

I'm currently going through Gibson's book, and I am super confused about the difference between differential and incremental backups.

Here's the definitions as provided in Gibson's book.

Differential backup- This backs up all the data that has changed or is different since the last full backup.

Incremental backup- This backs up all the data that has changed since the last full or incremental backup.

Deciding to include a word in the definition of that same word drives me nuts. Could anyone here help me understand what the actual difference between these is?

paul78

The key is what was last backed up.

For a differential backup - it's all the new files and changed files since the last FULL backup.

For an incremental backup - it's all the new files and changed files since the last backup.

So for example:

File A, File B, File C - Full backup is done

File D and File E are added so now we have File A, File B, File C, File D, and File E.

For a differential backup - the following files are backed up:
File D, File E

For an incremental backup - the following files are backed up:
File D, File E

Let's say we now add new file File F.

For a differential backup - the following files are backed up:
File D, File E, File F

For an incremential backup - the following files are backed up:
File F

Hope that makes sense.