Choosing between CBT or Hot Add transport mode?

[james411]

Hello all,

Hoping for some input. Here is my environment: small VMware shop with 2 ESXi 5.0 hosts and Veeam 6.5 patch 3. Host1 will only be running one VM (a SBS server). Host 2 will be running 4 VMs including the VM running Veeam Server. My backup repository will be on a local NAS device.

As this is a small environment, I plan on using the Veeam server as the default backup proxy. As I understand, as Veeam server is a VM on host2, it will be able to backup host2 VMs using hot add mode. So far so good. My dilemma is with host1 that will only be running one VM. I was going to make this VM a backup proxy as well so the proxy could operate in hot add (or virtual appliance) mode. But upon further research, it appears that a VM that acts as a backup proxy using hot add mode, cannot use CBT. Correct?

So I am wondering, given the setup I've described, would it be best to make the VM on host1 a backup proxy and forgo CBT or just use the backup proxy on the Veeam server on host2, this way I can take advantage of CBT, but would be using network mode for the transport?

Thoughts are welcome. Thanks so much!

[veremin]

Hi, James.

Yep, you’re right in your assumption that CBT can’t be utilized while Hot-Add proxy servers are backing up themselves.

So, I would recommend stick with Network scenario, because without CBT VB&R would use built-in mechanism and waste time reading whole VM image in order to understand what block have changed since the last run, etc. As you might imagine, it’s quite a time consuming process.
In such a small production, network mode should be more than enough.

Thanks.

[foggy]

You can also explicitly set the transport mode for that proxy to Network and enable CBT manually on it and the proxy VM will back up itself using CBT. Just in case you will need to have a proxy on the first host for some reason.

[james411]

Foggy that is a good thought if I want a way to put a backup proxy on the first host to take some load off of the second. One other thought for you guys: would you expect a backup proxy backing up a Vm using network mode as foggy described to be any faster than say if that proxy was on another host that uses network mode? Put another way, would you expect foggy's scenario to be faster than the one I originally planned on or is network mode network mode and it doesn't matter if the proxy is on the actual host it happens to be backing up?

[veremin]

It depends on type of connection you have between two hosts.

In order to understand better it might be worth imagining the traffic flows in both cases. In the first scenario, the data will have to cross a link between ESX(i) hosts in uncompressed state in order to be sent later to NAS repository by proxy that resides on the other host. Meanwhile, in second case, the proxy will reside on the same host a source machine does, and this allows you to compress the data prior to sending it to NAS repository.

However, in the situation with a tiny shop, it’s unlikely to change something, since we are talking here about pretty small production, where abovementioned factors don’t play a crucial role.

Anyway, it stands to reason to try and compare the results you get.

Thanks.