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-701 Backup error

1. Insufficient space for shadow copies

If the error happens during the backup process, the VSS shadow copy space reserved by Windows could be full and during the backup, Windows deletes the temporary backup VSS snapshot and the backup is aborted. In this case make sure that there is at least 5 or 10% free space on the source drives. Then increase the shadow copy space on these drives. 

In the following example we increase the shadow space on drive C: to 10%.

  1. Start the command prompt as administrator.
  2. Enter this command vssadmin Resize ShadowStorage /For=C: /On=C: /MaxSize=10%.
  3. To increase without size limitation use the command vssadmin Resize shadowstorage /For=C: /On=C: /MaxSize=UNBOUNDED.
  4. We recommend setting the shadow copy memory between 10 to 15%. If you have larger data volumes and do not use the Windows own shadow copy function, you can set the shadow copy memory to unlimited.

Note: If the commands do not work, you can change the values using the Windows graphical console:

Start the Windows File Explorer and select the C: drive by right-clicking it and select "Configure Shadow Copies" (for desktop operating systems via "System" -> "Computer Protection"). 

For older server operating systems, select drive C: by right-clicking -> "Properties" and then select "Shadow Copies" tab. Then select the drive and set the desired size via Settings.


2. Problem with source or target disk

There is a problem with the source or destination disk that is a file system error or the hard drives/SSD have bad sectors. Check in the Windows Event Viewer of this system, at the "System" item in the Windows Event Viewer you will find if you filter for errors, warnings, critical in this case disk, controller errors, file system errors and similar. Also check the SMART values of the affected disk to better isolate the cause of the error. 

Depending on the degree of damage, it may be necessary to replace the affected media with new, error-free media, as this is a hardware issue. If the error occurs when restoring, check in the image management with the function "Verify" whether the backup is completely readable.


The error you are experiencing means that your backup target storage does not have enough free space. Check the backup target storage and adjust the retention policy in the backup software to automatically delete old backups, or use a larger backup target storage if you want to keep more backups for a longer time.