running Backup and Replication on the same VM(s)

[Zep]

Hello,
I've spend some hours now reading the Veeam documentation, the Forum's FAQ, the Veeam forums and "Googeling" around as I am new to replication.

The reason is I have seen the following setup in another site I give some help from time to time:

- one or more VMs on ESXi-Host-1
- running a Backup Job once a day to send VM backups to a repository
- running a Replication Job every two (2) hours to send data to replica VMs on ESXi-Host-2

I do understand that there is a way to feed the replica VMs from the backup data, but I don't understand how Veeam can keep the backup chain and the replica VM's chain consistent using CBT with the setup above.

The forum's FAQ says:
"There will be no issues, as changed block tracking is designed to handle such usage scenarios."

Does the CBT provide multiple "streams" to track the changes?
What happens when somebody runs a backup job using the option to "reset" the CBT? Shouldn't this affect the replication as well?


Appreciate any help to answer this mystery

Regards, Zep

[ronnmartin61]

From https://kb.vmware.com/s/article/1020128

When software performs a backup, it can request transmission of only the blocks that changed since the last backup

or replication in our case

[Zep]

Thank you for responding, Ronn.
I do understand the basic use of the CBT, but my question is about double-use of the CBT for Backup together with Replication.

Regards, Zep

[foggy]

There are no issues in such running both backup and replication jobs against the same VMs in terms of CBT - as mentioned, it is designed to handle such scnearios. Of course, if some job resets CBT, then this affects all other jobs as well - during the next runs CBT will return more data.

[PetrM]

Hello,

As far as I understand, the idea is to run replica from backup? In this case, you should not worry about CBT neither as data is retrieved from already existing backup files and not from production.

Thanks!

[Zep]

Hello foggy,

thank you for the hint about CBT resets. Appreciated.


Hello PetrM,

no, my concern was to read the data for backup and replication from the same VM side by side.
I still can't imagine how this works exactly, but I think I can live with that


Best regards, Zep

[veremin]

Have you checked the referenced thread where Andreas explains how CBT handles such cases? Thanks!

[Zep]

Opps, I must have confused this thread with a different one I had in mind.

Now I understand it. Thank you for the reminder!!

[veremin]

You're welcome. Glad we have clarified the confusion