Server Backup Not Enough Space on the Disk-Explained and Solved

Posted by @Cody

May 14, 2018

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.

The Symptom

Generally, Windows Server Backup (WSB) has Automatic Disk Usage Management feature to delete the oldest backup by default. However, you may still encounter WSB failed with the following error:

“Windows Backup encountered an error while writing to the backup target. Detailed Error: There is not enough space on the disk”

The Cause

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 will not shrink the diff area less than 1/8 of Target volume size in case of losing all the previous backups. This is why Windows Server Backup failed with not enough space on disk.

The Solution

If you happen to receive this error with WSB, you have three options to get this resolved.

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

2. Exclude some items that you are backing up.

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

The first two are easy to follow, but you may not want to. So how to remove snapshots? If you are using Windows Server 2012(R2) or Windows Server 2016, you can use wbadmin delete backup command to remove old backups. There are three 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 provide commands that allows you to delete system state backup with WBadmin. Usually it is non system state backups that take up the space because system state backups take less space. To delete snapshots, you need to use diskshadow.exe. You can run the following command from the standard cmd prompt.


>list shadows all

>delete shadows id <ShadowID> => To delete a shadow copy of the specific ID


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


>delete shadows oldest <targetvolume:> => To delete the oldest shadow on a target volume.

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

Long-term solution

If you are not content with the performance of WSB, you can try dedicated Windows Server backup software, AOMEI Backupper Server. It allows you to perform System Backup, Disk Backup, Partition Backup, and File Backup. Its Disk Space Management that deletes the previous backups works smoothly no matter how many versions of backup you have created. Besides full backups, you can also create incremental/differential backups.

1. Download and run this Windows Server Backup alternative software.

2. Under “Backup” tab, select “System Backup”. You can also select other three backup types based on your needs.

System Backup

3. Click “Step 2” to select a target location to receive the image backups as the needed partition(s) will be included in “Step 1” automatically.


4.       To configure a schedule backup, you can click the “Schedule” button down the left bottom.


5.       After that, you will see the “Scheme” option in which you can enable Disk Space Management and choose one of the 5 ways of how to delete the old backups. Then click “Start Backup” to save and run this backup.

A system backup or disk backup created with AOMEI Backupper can be restored to dissimilar hardware computer besides the original computer. With AOMEI Backupper and its Disk Space Management feature, you will never meet the Server backup not enough space on the disk error.