For backup and replication scenarios involving Hot Add, we would like to ask Veeam to implement a simple option in the job, which would let the admin prevent VBR from cloning the BIOS UUID of a VM. Why?
Because apparently, vSphere systematically changes that ID upon cloning a VM (to keep these distinct), but yet VBR circumvents this mechanism (when performing a replication job), which in turn causes erratic behavior of the VBR proxies.
It is apparently not an issue when replicating non-proxy VMs. However in the case of proxy replications, if the BIOS UUID of the target (replica) is identical to that of the source VM, then when VBR invokes a proxy for any job, it retrieves the proxy list based on the BIOS UUID, which means that it may see several identical ones (one of which would be the running proxy, but unfortunately the other identical ones would be its dormant replicas!).
The consequence is that VBR will then potentially and randomly pick one of these inactive proxies and ask vSphere to attach the disks of any job to the wrong proxy VM (a dormant replica of the actual proxy VM), which obviously won't allow VBR to leverage the needed compute resources of the proxy (since it is down), and will result in VBR failing over to Network Transport mode.
This can be easily avoided by ensuring that any replica has a distinct BIOS UUID than its source VM, which apparently is the vSphere default when cloning an VM (before VBR changes the BIOS UUID back to what the source VM has). Better even, if Veeam determines that this request should not be an optional box (which the admin decides to check), but rather a default (automated by design), then that would be event simpler, less confusing and more dependable.
Thanks for looking into it, Gostev. We understand Veeam recommends to leave VBR or its proxies on physical hosts, but we are 100% virtualized and we believe that VBR should be able to fairly easily backup any VM, even itself. We know it is capable of doing it, and that is why we would like to request that VBR be slightly adjusted so as to enable that capability.