Fix Windows Server Backup Failed Not Enough Space on the Disk

You may get the Windows Server Backup not enough space on the disk error after running a few versions of backup. Why Windows Server Backup failed? This article will explain it and provide solutions. Applied to Windows Server 2008, 2012, 2016, etc.


by Delia Updated on October 18, 2022

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Windows Server Backup: There is not enough space on the disk

Generally, Windows Server Backup (WSB) has an Automatic Disk Usage Management feature to free up disk space. When you configure a disk for scheduled backup, it will automatically reuse the space occupied by older backups when creating new backups. However, you may still encounter WSB failed with:

“Windows Backup encountered an error while writing to the backup target. Detailed Error: There is not enough space on the disk” or "There is not enough space available on the disk(s) to complete this operation."

windows server backup disk full

Many users are confused as to why the problem occurs and how to resolve it. Keep to reading to get the answer.

Why not enough space on the disk

WSB saves snapshots in the diff area. The Automatic Disk Usage Management, which is enabled in WSB by default, will shrink the diff area and remove the corresponding backup file to free up space for the next backup.

However, WSB checks if the diff area can free up enough space before shrinking. And there's a general rule you should know that it will not shrink the diff area to less than 1/8 of target volume size. This is to ensure that you do not lose all your past backups in order to proceed the new backup.

Due to this rule, Windows Server Backup sometimes fails to not enough space on disk error, despite the automatic disk usage management feature.

Solutions to server backup not enough space on the disk

If you happen to receive this Windows Server backup failed not enough space on disk error, you have three options to get this resolved.

>> Solution 1. Use another larger hard drive as the backup disk.

>> Solution 2. Exclude some items that you are backing up.

>> Solution 3. Manually delete some old snapshots to free up space.

The first 2 are easy to follow, but you may not want to. So how to remove snapshots? If you are using Windows Server 2012 (R2), Windows Server 2016 or above versions, you can use wbadmin delete backup command to remove old backups.

There are 3 ways to determine which backup(s) to delete and the parameters are:

-keepVersions, -version, or –deleteOldest.

For example, to delete all backups except one that was created at 06:48 11/10/2015, use the following command:

Wbadmin delete backup -keepVersion:11/10/2015-06:48 -BackupTarget:F:


In Windows Server 2008/2008 R2, WBadmin only provides commands that allow you to delete system state backups, while it's usually non-system state backups that take up the space. So to delete snapshots in earlier versions, you can use diskshadow.exe. Run the following command from Command Prompt:

  • diskshadow
  • list shadows all
  • delete shadows id => To delete a shadow copy of the specific ID

or delete shadows all => To delete all the listed shadows.

or delete shadows oldest => To delete the oldest shadow on a target volume.

Choose the proper way to remove snapshots or backups to free up space. After that, you should have enough space to create backups. The next time when backup disk is full, you can repeat these operations to free up more space on the disk. If you want to save the trouble of removing backups manually forever, you can try another backup tool with customizable retention policy.

Long-term solution | use Windows Server Backup alternative

If you are not content with the performance of WSB, you can try dedicated Windows Server backup software, AOMEI Backupper Server. Its Disk Space Management can help delete the previous backups no matter how many versions of backup you have created. You will never meet the Server backup not enough space on the disk error.

In addition, compared to WSB can only set one daily backup schedule, it allows you to create multiple schedules (daily/weekly/monthly/event triggers/USB plug in) to auto protect your system, important files, disk or partition. Besides full backups, you can also create incremental or differential backups to backup only changed data.

You can download the free trial to try it out:

Download Free Trial Win Servers & PCs
Secure Download

How to set scheduled backup task with automatic backup cleanup

1. Install and launch this Windows Server Backup alternative software. Select “System Backup” under “Backup” tab to back up the OS. You can also select "File Backup", "Partition Backup" or "Disk Backup" based on your needs.

System Backup

2. Click to select a target location to receive the image backups as the needed partition(s) will be included automatically.

Select Path

3. To configure an automatic scheduled backup, click the “Schedule Backup” button down the left bottom. Then click "Backup Scheme" to choose between full, incremental or differential backup, and enble "Automatic Backup Cleanup" to auto delete older backup images.

4. Click “Start Backup” to save and run this backup.

Start Backup


  • A system backup or disk backup created with AOMEI Backupper can be restored to dissimilar hardware computer besides the original computer, just tick Universal Restore at restoration.
  • To protect unlimited PCs and servers within your company, you may choose AOMEI Backupper Technician Plus. It offers unlimited billable technical services to clients. It also enables you to copy installation directory for portable version creation.

How it works to avoid server backup no enough space on the disk

To create a schedule backup task and set up the retention policy for your Windows server backups to prevent no enough space on the disk, follow the instructions below:

Schedule Backup

  • Daily/Weekly/Monthly: Once setting up, the backup task will running at a specific time, or daily, weekly, monthly to avoid backing up the same content manually.

  • Event Triggers: You could trigger the backup event by the following events: User logon, User logoff, System startup, System shutdown.

  • USB plug in: Once detecting the source or destination USB device of the task is plugged in, AOMEI Backupper will automatically back up the data on the USB or backup data to USB drive.

Schedule Settings

Backup Scheme

  • Backup Method: Select full backup, incremental backup or differential backup according to your needs.
  • Automatic Backup Cleanup: By enabling it, you can set up a retention policy to automatically delete older backups by quantity, by time, by frequency or by space. Check more details in backup scheme.

Backup Scheme


Now you know why you meet the Windows Server backup not enough space on the disk error and the solutions to figure it out. However, as long as you continue using WSB to backup your server, you may also meet the low disk space error sooner or later.

If you want to avoid this problem altogether, you can try another backup tool - AOMEI Backupper Server. Its Disk Space Management feature would automatically delete old backups to free up space. What’s more, it offers more useful functions compared to WSB, such as multiple backup schedules.

Delia · Editor
Delia owns extensive experience in writing technology-related blog posts, and has been a part of AOMEI since 2020 to provide expertise in data security and disaster recovery. She works with Windows operating systems, SQL databases, and virtualization platforms such as VMware and Hyper-V, specializing in troubleshooting and advising on data protection and migration.