Backup copy stops for 15 minutes between disks on a VM

[ers_kentwick]

Environment: Veeam 9 w Update 1
Backup from vSphere to a Windows VM (TVEMREP101) with local disks as a respository (the repository only holds 1 restore point). There are 6 VM's in the backup job, 4 at ~40 GB each, 1 sized at 80 GB and 1 sized at 850 GB (an Exchange server) (these are all incremental backups)
Tape job copies from TVEMREP101 to LTO4 tape just fine.
Backup Copy job copies from TVEMREP101 to local Data Domain for 35 day retention. The copy of the first 5 VMs ran fairly fast. However, I'm watching the Backup Copy for copying the 850 GB VM and it is doing one disk, waits about ~15 minutes, does another disk, waits ~15 min, etc etc.

While it is copying the disks Veeam reports a processing rate of > 100 MB/s. The Veeam log, right now, shows "Hard disk 4 (0.0 KB) 0.0 KB read at 0 KB/s". The TVEMREP101 isn't blocking it (I'm watching the vSphere performance graph and it isn't reporting any activity (CPU, disk, network). The Veeam Server and the four proxies that I have also report no bottleneck.

I'm failing to understand why Veeam is waiting between copying on each disk in the large VM.

Can anyone at Veeam shed some light on what the Backup Copy job is doing?

[PTide]

Hi,

Is there anything similar to "waiting for backup resources availability" in the session log? Have you checked the load on both source and target repositories? Do you have any throttling settings in place?

Thanks

[ers_kentwick]

Are there any messages? Nope, not a word.
What's the load on the source and target repositories? The Backup Copy job was the only thing running.
Do we have any throttle settings? Nothing beyond the defaults.

[PTide]

Do you have parallel processing enabled in the global settings? If not then please enable it and try to run job again. If it's already enabled then pelase install Update 2. If that won't resolve the issue please contact support and post your case ID.

Thank you