Problem
Job Fails with "storage unit concurrent jobs throttled by capacity management"
Solution
"storage unit concurrent jobs throttled by capacity management"
What was occurring is all the policy's had reserved the free space up to the high water mark which is a safeguard in the software.
By disabling Storage Unit Job throttling this allows all the jobs to use the space at the same time and then start draining images from the Storage Unit as it reaches the high water mark.
Please run this command to change disk stu throttling to YES and verify the job status.
nbemmcmd -changesetting -DISABLE_DISK_STU_JOB_THROTTLING yes -machinename <media_server>
If enabled, disables the disk storage unit job throttling that occurs when disk storage units approach their high water mark. Disk storage unit throttling limits the number of jobs that are started simultaneously to approach the high water mark more accurately. The default value is to throttle disk storage units approaching their high water mark.