What does the Backup Copy Job do?

[PariPari]

Hello,

we have a test running at customer site with a D2D Cifs Share as Repository (not optimal, I know).

Normal Backup operation to Repository runs fine at @60MB/s processing rate (96% Source, 28% Target).
But Backup Copy to Tape is slow.. very slow. 8MB/s if I am lucky, but source says only ~30% Activity (rest 0-1%). The backup starts ok (60mb/s for ~2-3min) and drops down to 5-15mb/s.
Pic: http://i.imgur.com/6wJYc7A.png

Backup Copy to tape from a (small) local repository runs at 135mb/s which is pretty nice.

So my question is: what exactly does the Backup copy do? Just reading the vbk from the repo and copy it over? Should be quicker then, even with cifs.

For the sake of completion:
It seems like it is happening since Patch 1. The very first backups mid dec where successful with 30-50mb/s (not fast, but still faster and successful).
I did also set the registry keys Datamoverlocalfastpath (2) and disaplepubliciptrafficencryption (1). Also SMB Signing is off per local policy.

[Shestakov]

Hello,
Backup copy job has 4 phases, including transform operations. The transform operations can take additional time doing a backup chain transformation and/or removing deleted VMs from restore points and/or compacting a full backup file, according to it`s own retention policy, which can differ from the source Backup job one.
What is the bottleneck of the job?
Thanks.