Differential Backup on Home 11.0
Win XP Pro - Backed up to 500 GB Ext. HD - Novice User: I have always used Incremental backups, but recently switched to Differential after reading the benefits. I thought I read that the Differential method checked for differences between the original Full backup and created a Differential backup showing the changes.
I noticed that every day I have two new Differential backup files, but the older Differential files are also there. Do I need the older Differential files? At two a day, they accumulate quite rapidly over a month.
Question #1: Can I delete the older Differential files or are they also needed?
Question #2: If the older Differential files are not needed, is there a way to automatically remove them when the new Differential files are created each morning?
I appreciate your help.

- Accedi per poter commentare

Thanks, GroverH. So, any differential files previous to the most current one are not needed; is that correct?
Sorry, I am a novice and am just trying to clarify your comment.
- Accedi per poter commentare

A differential backup contains all changes made since the last full backup. In order for any differential to be restored, all it needs is the original full backup plus any single differential that you choose.
Sunday--full backup
Mon-diff1--All changes since Sunday full
Tue-dif2--All changes since Sunday full
Wed-dif3--All changes since Sunday full
Thu-dif4--All changes since Sunday full
Fri-dif5--All changes since Sunday full
Sat-dif6--All changes since Sunday full
In order for any differential to be restored, all it needs is the original full backup plus any single differential that you choose.
Of course, keep in mind that if you choose to delete earlier diff file, you won't have what the content was before the change--only the final result. For example, lets say you edited a file and deleted a paragraph on Thursday and then took a new diff backup. A restore of the newest diff file will show that the paragraph is gone but you would need an earlier diff file to know what the content was of the paragraph that was deleted.
In the above example, you could delete all but Sat-dif6 and the missing files would not affect your ability to restore the diff6 plus the required original full backup.
An incremental type backup to be restored needs not only the first full backup but all prior incremental. If you wanted to restore inc7, you would need to retain inc2-6 as well.
- Accedi per poter commentare

Thanks for being so patient with me. I thought that is what you meant, but when dealing with backing up my hard drive, I felt it would be better to be safe than sorry.
- Accedi per poter commentare