To determine if sufficient disk space is available on the target volume for the restore:

1. Estimate the amount of data that you are restoring. You can do this by viewing size properties for the backup set in Backup Exec.  For more information, see https://www.veritas.com/business/support/index?page=content&id=HOWTO74380
2. Determine the amount of free space available on the volume.
3. If sufficient free space is available, run the restore job.
4. Following the restore, run Microsoft Data Deduplication optimization and garbage collection jobs which are run via Powershell. For more information on these Microsoft Data Deduplication jobs, see https://TechNet/en-us/library/hh831434.aspx

If sufficient free space is not available, you can try running the Microsoft Powershell commands for Data Deduplication optimization and garbage collection on the volume to free some space.

If sufficient free space is still not available on the volume after you run those jobs on it, you can try redirecting the restore to another volume which contains ample free space.

Alternatively, you can try creating individual restore jobs that contain subsets of the data that you want to restore.  Following each restore job, run Data Deduplication optimization and garbage collection jobs to incrementally free some space on the volume.

When restoring data to a Windows Data Deduplication volume, you must determine if sufficient free space is available on the volume to which you are restoring the data. The restore job may fail if the volume does not contain enough free space. Backup Exec backs up and restores optimized Windows Data Deduplication volumes in unoptimized format which requires significantly more space, depending on the amount of data that you back up or restore.