synthetic full not in backup copy job

[brucquat]

Hello,
In our backup jobs, we perform a synthetic full every Saturday. We have also corresponding backup copy jobs to copy to a repository located in the 2nd site.
Afterwards, only the Full backups from the second site should be saved to physical tapes (also located in the second site).
But in the destination repository (backup copy jobs), all synthetic full backups are not present like in the source repository (backup job).
Looking at the documentation, it seems to be an expected behavior "Veeam Backup & Replication does not copy restore points that are locked by the backup transformation process (merge, transform).".
However, I do not understand the relationship between the contents in the "source" repository (backup job) and the contents in the destination repository (backup copy job).
Example: Retention period 14 days, Synthetic Full every Saturday, immediate copy (mirroring) for the backup copy job
These are the contents that we have in both repositories:
Source Repo: VBK 22/1, VIB 23/1->28/1, VBK 29/1, VIB 30/1->4/2, VBK 5/2, VIB 6/2->9/2, VBM --- Clear for me and expected in the Source repo
Destination Repo: VIB 28/1 (3 times), VIB 29/1->6/2, VIB 8/2, VBK 8/2 (filename with "2022-01-28"), VIB 8/2, VIB 9/2, VBM --- Unclear to me in the Destination repo
Questions:
- Why 3 VIB files with date modified on 28/1?
- Why VBK file with date modified on 8/2 (Tuesday)?
- Why the VBK file with date modified on 8/2 has in its filename "2022-01-28"?

Many Thanks.
Best Regards

[foggy]

The backup copy job has its own backup chain and retention on the target repository. It doesn't mirror the source backup chain, it copies the restore points appearing on the source immediately, but maintains its own chain on target. File dates on target change as the files are modified due to the increment is being merged into the full backup file, while the file name itself doesn't change.

[brucquat]

Many thanks for your answer.
Then, now my question is how can I understand/predict how the backup chain in the destination repo (backup copy job) is built?
The retention policy of the backup copy job is 14 days (like in the backup job)

Thanks.

[foggy]

You can review this user guide section for the process description and then ask if something is not clear.

[brucquat]

Thank you. Got it, for the backup copy jobs, it creates forever forward incremental backup chains.
However, now my concern is the following:
As stated above, the goal is to perform a backup to tape from the backup copy job to avoid intersite traffic. In the source backup job, we create a synthetic full every Saturday while the other days incremental backups are scheduled (forward incremental). In the backup copy job, the backup chain is different.
What is your recommendation to put a full backup to tape once a week from the backup copy jobs?
Thanks
Regards.

[veremin]

Use virtual full backup - feature that allows tape job synthetically create a full backup on target tape, using forward forever incremental source backup chains.

Going forward we'd better switch the discussion to the dedicated subforum for all tape-related questions.

Thanks!