The new Backup program included in Windows 7 has been one of the most touted features of the popular new operating system from Microsoft. But it turns out that it does not appear to be as good as we thought. Here’s why: Windows 7 Backup lacks the ability to delete older backup files to make room for the new backup files. In other words, the backup location will fill up, eventually!

Confirming this is a post dated November 2009 on the Microsoft Technet web site:

Hi folks. I was told that the Windows 7 backup will automatically delete space as needed when it runs out but this morning I am being told from the Action Center that there isn’t enough room. Do I have to manually delete backups? I will note that I am backing up to a network location. I don’t know if that makes a difference. Thanks.

The answer, coming from a Microsoft representative, states that you must manually delete the old backup sets!  Here is that reply:

That is true. However, we recommend that you run both file and system image backups. File backups are handy when you just want to recover some files and not your whole system.

How often are you hitting this problem of disk full? Just to clarify, once you hit a disk full, you do not have to delete everything and start over. Open Backup and Restore Control panel -> Manage space -> View Backups. This will show you all the backup sets (every backup set is a full + set of incremental backups) for different backup periods. We recommend that you only delete the older backup sets. This way, the current backup set is still available and the next backup that runs is only an incremental backup and not a full. Please let me know if this helps you.

Thanks,
Sneha
[MSFT]

Here is another post that confirms this is the case. This includes the reference that explains the steps for manually deleting old backups – or “managing backup disk space” as Microsoft calls it.

I hope to come up with a solution that will allow automatic management of  the old backup files from Win7 Backup, but so far, that solution evades me.  I believe that I will soon be switching back to a different backup solution.