What happens when a Windows 7 backup disk is full? I've been trying to find documentation on the issue without success. Does Windows 7 automatically delete the oldest backup files to free up space or does it force you manually pick and choose which files to delete?

Time Machine automatically deletes the oldest copy of files, but as far as I can tell Windows 7 makes you manually choose. I keep getting a running out of disk space for backup notice on Windows 7 without any option to not warn me and just delete the oldest files automatically...

5 Answers 5


In my own experience (the drive holds other data too, virtual machine hard drives, ISOs, etc.) Windows 7 did not delete the old backups automatically. On the next scheduled backup it errored out with "Not enough space available on the backup volume."

My backup drive only has about 120GB available and 60GB is the system backup, so it may just be my current setup that caused it to fail. I've been backing up since the first week of September and it happened for the first time two weeks ago, so thankfully it isn't a constantly occurring issue.

  • 1
    So you manually deleted several gigs from your backup drive to get it going again? That's quite annoying, I wish there was an automatic option, that way even if you used a small backup drive, you could basically keep it maxed out all the time (thereby keeping as many backup copies as possible) and let Windows delete just enough to store the next backup. Having to do it manually means deleting enough of the old back ups so that you aren't constantly pestered and thereby keeping fewer backup versions of files over all.
    – Choy
    Jan 23, 2010 at 6:39
  • I was expecting to have it happen automatically as well. I deleted the older backups using the Manage Space link on the Backup & Restore control panel. Under the System Image settings window I originally had "Let Windows manage the space used for backup history (maximum 69.87GB)" selected, once I ran out of space and cleaned up old backups I now have the "Keep only the latest system image and minimize space used by backup." option selected. Currently my data backup is 17GB (from 12/6/09 to 1/17/10) and there is 58GB left, so we'll see what happens in the future as it's used up.
    – Joshua
    Jan 23, 2010 at 9:33
  • One of the reasons I use Windows Home Server is for the backup rotation it does automatically. My WHS handles all my Windows 7 and stores my Snow Leopard backups via Time Machine, with disk duplication on both. Feb 22, 2010 at 16:06

How much storage space do I need to back up fie?

That depends on the size of the files you back up. We recommend that you save your backup on an external hard drive that can hold at least 200 GB. Windows Backup keeps track of the files that have been added or modified since your last backup and then updates the existing backup, which saves disk space. You can manage the disk space that is used for your backups by doing the following:

  1. -> Click to open Backup and Restore

  2. Click Manage space. If you are prompted for an administrator password or confirmation, type the password or provide confirmation.

    Note • If you haven't set up backup, you won't see Manage space.

  3. To delete older file backups, under Data file backup, click View backups.

    You can then select the file backups that you want to delete, which will free up disk space. Deleting an entry in the list will not have an impact on other backups. If you think that you don't need a version of your files from a certain backup period, you can delete that backup. We recommend that you always keep the most recent backup.

  4. To change the amount of space that is used by system image backups, under System image, click Change settings.

    You can then choose to have Windows save older system image backups or just the most recent system image backup.

  • I deleted my answer and edited yours.
    – Moab
    Aug 28, 2011 at 0:22

The problem may be your backup scheme. Check out what is being backed up. Many programs will backup all the browsers caches and Windows temps files and junk that isn't needed. Make a setup that will run ccleaner before backing up. Also, use incremental backups. You will use much less space.

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    "Many programs will backup" - this is a question about Windows 7 backup, not some third party program.
    – Dennis G
    Sep 20, 2011 at 15:57

Does the registry tweak given in the fourth comment of this page help?


That is, if enabled the automatic full backup will take place by default after 365 days, which means during that time the incremental backups will fill up the backup disk?

Are all previous full and incremental backups deleted when an automatic full backup takes place?

  • Can you please include the most relevant info from that link here, on site? Thank you!
    – slhck
    Jul 16, 2012 at 22:27
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    This question seems to be in jeopardy of not looking like an answer.
    – Journeyman Geek
    Jul 17, 2012 at 14:55

I have just written a script which can be called from Task Scheduler and which will prune your windows backup directory to delete older Backup Sets. You need to add a registry entry to get Windows Backup to create backup sets more frequently than once per year.

The script, registry entry and an example Task Scheduler xml file are available on GitHub.

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