Maybe you're going to laugh about this one, but still
I am actually thinking about something that I have a use case for. Let's consider just two ESXi hosts. Both of which I'm backing up with Veeam B&R. Veeam B&R Server is actually just a VM running on one of those two hosts. On both hosts I also have a separate VB proxy VM, because of security and better speed to the NAS. Having a Veeam Server in a VM on of those hosts means I want to have a replica of that VM. Obviously, I don't want to waste time by rebuilding the Veeam Backup VM in case I really need it (that would be in the case the host where the Veeam Server VM is located actually dies). So it's a proper candidate for a replica.
Of course I should have the Veeam B&R on a third, separate host. But even in that case I still might want a replica of it, right ? Why not ? Ok not really the same situation, as chances are that the third host will not fail at the same time as the host I'm trying to protect. Of course this is not the recommenced setup, but world is not perfect, so let's skip obvious comments and consider this for a moment.
In such setup, is it possible/viable to plan a replication job for the VM that holds the actual Veeam Backup Server ? Does that have any good chance of working as expected ? Again, I have a separate VM with VB proxy on this host, so that's supposed to do the actual replication work, but VB server still is the machine I'm trying to replicate. If it completes (I didn't test yet but I see no reason why it wouldn't complete) - question is in what state would the B&R VM replica find itself when I power it on the new host ? I guess, as the backup would have started on that machine (as it's a VB Server), the replicated machine, when started, would find itself in a state when snapshot was taken. And that would probably be in the middle of doing backup - of itself. So... what can one expect ? Would it try continue/finish that backup when started ? Would it just fail the job as the source is not reachable ? Would something seriously screwy happen ? Or could this actually work ?
I know this is probably not the best idea, but I'm interested in hearing your thoughts.
On surface, it sounds cool anyway. You only have two hosts and your VB Server is in one of them, but you can replicate it

so if one fails, the other host has a ready-to-use replica of Veeam B&R Server. It does sound cool, but what about real life. Possible ?