Incremental/Differential

I am so confused with the two. Can someone please explain the difference between the two.

I did read the guide but didn't make much of it.

 

An incremental contains changes based on the previous incremental image.

A differential contains changes based on the original image.

In other words, each incremental depends on ALL previous incremental images plus the base image for you to restore the drive. Whereas you only need the last differential and the base image to restore the drive.

 

Think of Incremental as a long chain. You need all links in the chain (all Incremental images and the original Full image) to restore the latest backup.

Differential is just the differences between the latest backup and the original Full image. You need only the Differential and the original Full image to restore the latest backup.

A Full image backup is complete and self-contained. You need only that one file to restore the latest backup.

 

Another way to look at the differnce between incremental and differential backups is that the file archive flag, which is set by the OS when a file is added or changed, is cleared at the end of an incremental backup; not so after a differential backup. The archive flag is used by both processes to know which files were added or changed since making the last full baseline backup.

Incremental has the edge of being able to revert back to a specific file version captured by an earlier incremental backup for a given baseline. Differential backups can take up less space than multiple incremental backups, especially when two or more file updates for one or more specific files are involved (and captured incrementally).

 

While your description expands on the difference, TI does not use the archive bit. It has its own mechanism for determining which files or sectors need to be backed up.

 

What if after a month I created a new full image? will the scheduled differentials base their backups on the new full image created?

 

As long as the name of the image file is exactly the same - yes.