Not enough space to perform backup error message can appear due to lack of space in the destination drive or in the temp files folder or the drive not available at the time of the backup to resolve this problem, you can

  1. Check your backup destination if it has enough space as the estimated backup size when the confirming data selections dialog appears. If you do not have enough space you can enable multi-drive spanning from Where to Backup page Enable Multi-drive spanning.
  2. Make sure your drive is accessible at the time of backup.

  3. Make sure you have enough space in the Temporary files folder (TempGS); it has to have enough space for the largest file you backup.
    You can allow GBM to auto-select the temporary folder’s location, as it will select the drive that has the most free space, or you can manually select the location from tools >> 
    Global Preferences >> General >> Under “Temporary files folder”, select “Use the following temporary location” >> Browse for the local drive with the highest amount of free space.
  4. If you are running incremental, differential, or mirror backups and GBM is reporting the size of a full backup, please make sure that GBM is resetting archive bits, if you are backing up from network locations, please refer to the following knowledge base for resolution:

APPLIES to GBM 7 and above