Veeam Replica and VMware CBT

[thomas_brun]

Hello everyone

I observed an odd behaviour in my backup/replica environment.
Our backup concept is backing up the active site by Veeam, copying the repository via Veeam copy job to the backup storage on the cold site and then replicating it via Veeam replica job to our VMware Cluster on the cold site.

Regarding CBT: With a normal Veeam backup job, CBT is enabled on the VMware VM. This is working fine on both sites. But CBT is not enabled on the replicated VMs in the cold cluster. Nonetheless, the replica job says CBT is enabled.
I now manually configured CBT on every replicated VM, where it was missing on 99% of the VMs. We have huge snapshot removal times on replica jobs (triggered by Veeam retention policy ofc) and I hope this is getting better now.

Is this a bug, my partially unpatched system (see software versions below) or just me not understanding some basics? Can somebody relate to this?

Our Software Versions (if this is important for some points):
ESXi 6.5 EP 23
vCenter 6.5 U3m
Veeam Backup & Replication v11.0.0.837 P20210525
Backup Server & Proxies are virtual Servers 2019 Std KB5004244 (July 2021)
Backup Storages are QNAP TVS-EC2480U-SAS-RP with Version 5.0.0.1986
Backup Repositories are ISCSI mapped LUNs from QNAP on both sites for REFS (mapped to 2019 Servers, version see above)

Sadly I am not authorized to decide when to upgrade software versions, except for emergencies. So I am not able to test this with newer VMware system versions.

[thomas_brun]

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

This article helps checking if the VM has CBT enabled or not.

[Andreas Neufert]

Replica targets VMs do not need CBT.
To be able to enable CBT, the VM has to be running, which is not the case in case of replicat targets.
Anyway Snapshot consolidation time has as well nothing to do with CBT usage or not.

[thomas_brun]

Alright, thanks for clarification.

/closed