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Old backups typically will have all of the files that were on your machine at the time the backup was taken.
I'm using Windows Vista. I back up to an external drive. When I later delete files from my C drive, will those deletes be removed in future backups on the external drive? I don't want to restore files that I no longer want.
Well, it really depends on exactly what kind of a sequence that you're doing here and what backup software you're using. But I can tell you in general what happens.
Once you back something up, files are not removed from previous backups. They remain there and that's important, as we'll see in a moment. What does happen is that when you make a future backup, the file is not present. In other words, the file is not backed up again.
If you were creating an incremental backup? Well, the file is not there, so it's not backed up again. If you create a new system image, it's not going to get backed up. But in those older backups? The file remains.
That's important for a couple of reasons. One of the things that backups protect you from is an accidental delete. This happens all the time. In fact, backups are more often used to recover accidentally deleted files than for any other purpose. After the file had been deleted, you will want to make sure that subsequent backups did not delete that file from prior backups.
The other is that... well, sometimes it's not so much an accidental delete as an uninformed one. A week, a month, or even a year from now, you might want to go back and recover that file. Backups can do that as long as they don't delete files from old backups - and they don't.
How do you really get rid of those files if you don't want them to be in your backups? Well, you said you don't want the file to be restored if you don't want to use it anymore.
All that really means is that you need to choose a backup image or a backup point that you would then restore to after the file was deleted.
So let's say the files existed on Monday; you deleted it on Tuesday and you took a backup on both Monday and Wednesday.
The Monday backup would include the file; the Wednesday backup would not. It doesn't matter if it's an incremental backup or a full backup. If you were to restore your machine to the backup that was taken on Monday, the file would be restored. If you were restoring your machine to the backup that was taken on Wednesday, the day after the file had been deleted, the file would not be restored. The file might still be present in an older backup, but the fact that you're restoring to a backup that was taken after the file was deleted will prevent the file from being restored.
Many people are concerned about making sure that a deleted file is truly deleted. Sometimes, they have a personal issue, security issues, or legal issues for making sure. That can get difficult. But, one of the places that files are often found after you think you've deleted it are in old backups. The only way to make sure that it doesn't happen is to delete the old backup.
I don't recommend that you do that unless you have a very specific reason for wanting to make sure that that file is absolutely no longer recoverable. Old backups... You're throwing out a lot of information that you may end up wanting someday just to get rid of that one file.
In some cases, I get it; it's important but that's what you have to do. You actually have to go back and delete the old backup in order to get rid of that copy of the file. It is typically not possible, or at best infeasible, to go into an old backup and delete a specific file from that backup. It's very time consuming, if it's even possible.
So, remember that the old backups typically will have all of the files that were on your machine at the time the backup was taken. Newer backups will not contain that file. The file may still be there in the old backup but the newer backups won't have them. If you don't want that file restored, make sure that you're restoring to a backup that was taken after the file had been deleted.
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