How to isolate NBD backup traffic in vSphere


Userlevel 7
Badge +6
  • Veeam Legend, Veeam Vanguard
  • 694 comments

A new feature in vSphere 7 is the ability to configure a VMkernel port used for backups in NBD (Network Block Device) respectively Network mode. This can be used to isolate backup traffic from other traffic types. Up to this release, there was no direct option to select VMkernel port for backup. In this post I  show how to isolate NBD backup traffic in vSphere.

Configuration

It is quite simple to configure backup traffic isolation. With vSphere 7 there is a new service tag for Backup: vSphere Backup NFC. NFC stands for Network File Copy. By selecting this, vSphere will return the IP address of this port when the backup software asks for ESXi hosts address.

So all you need to do is to add a new VMkernel port, enable Backup service and set IP and VLAN ID. Host does not need to be rebooted. Now NBD backup traffic will be routed through this port.

 

 

 

How does it look like

For verification there are a few options. You can check log file or monitor ESXi network throughput. On my demo ESXi host, I created a VMkernel port vmk2 with backup tag. IP of this port is 10.10.250.1.

Log file

Probably your backup software create logs for each backup process. In case of VBR, a few log files are created. To get the information, what IP is used for backup traffic, you can search in log files: Agent.job_name.Source.VMDK_name.log in directory C:\ProgramData\Veeam\Backup\job_name of VBR server.

In the appropriate log file, you see IP address, returned from vCenter to connect for backup traffic. Here is a screenshot with enabled backup tag.

Compared to no tagged network port:

 

Monitor ESXi network

For realtime-monitoring I prefer esxtop in ESXi console. In this screenshot you see backup traffic on vmk2:

Compared to no tagged port for backup:

 

Veeam preferred Network

Question may arise, if it is possible to select ESXi VMkernel port with VBR natively. For this, I tried to use Preferred Networks to define my network of choice.

Answer: this does not work, backup traffic is still routed through the default management port of the host.

What about other way round: can preferred networks prevent the selection via tagging VMkernel port? The answer here is also no. Even if management network is configured as preferred, tagged port is used.

 

For more information - for example command line options - visit 

https://vnote42.net/2021/05/31/how-to-isolate-nbd-backup-traffic-in-vsphere/

 

[update; 20.07.2021]

It has turned out that there are issues with isolated backup traffic that is routed. In this situation, ESXi is not working as expected. I could re-create this situation in my lab; behavior was just strange!

According to VMware Support this will be re-viewed internally. So for now: do not use this feature, if you have to route the isolated backup traffic.


16 comments

Userlevel 7
Badge +3

Good one !

Userlevel 7
Badge +5

Great article @vNote42 

Userlevel 7
Badge +3

Nice reading as always @vNote42 

Userlevel 6
Badge +1

Thanks @vNote42 

Userlevel 7
Badge +2

Nice post @vNote42 !

Cheers!

Userlevel 7
Badge +4

Amazing content as always Mr @vNote42 

Userlevel 7
Badge +4

Perhaps I ammissing something, but why should I do this? It is used for NBD traffic only, if I understand correct.

We have configured two VLANs to our backup proxies and server. The vCenter management LAN connection  and a dedicated backup LAN connection. The backup VLAN is the prefered network connection in Veeam. So all backup data traffic is routed over the backup VLAN and the management data is routed over the management  VLAN.

 

Userlevel 7
Badge +5

Perhaps I ammissing something, but why should I do this? It is used for NBD traffic only, if I understand correct.

We have configured two VLANs to our backup proxies and server. The vCenter management LAN connection  and a dedicated backup LAN connection. The backup VLAN is the prefered network connection in Veeam. So all backup data traffic is routed over the backup VLAN and the management data is routed over the management  VLAN.

 

I believe it is because even with the preferred network set up it will not use it and uses MGMT network for your hosts regardless as noted in the “Veeam Preferred Network” section.

Userlevel 7
Badge +4

Mhh…. the management traffic is routed over the management network, but the data traffic is routed reliable over the backup network.

And do I really want to use NBD only? We have a difference of at least one to five  - in some environments of one to ten - in speed between NBD and hotadd mode…

 

Interesting topic to discuss with all the architects here I think 😎

Userlevel 7
Badge +5

Mhh…. the management traffic is routed over the management network, but the data traffic is routed reliable over the backup network.

And do I really want to use NBD only? We have a difference of at least one to five  - in some environments of one to ten - in speed between NBD and hotadd mode...

I agree HotAdd is the way for speed, etc. but I think this was if Veeam cannot do one of the faster modes and defaults to NBD that it separates the traffic from management.  I need to test this in my lab and see what happens.  :grinning:

Userlevel 7
Badge +3

Hi @vNote42 , thx for sharing. I did not know it already that this is possible in vSphere right now. I always use and recommended my colleagues to use Hot-add method. I’m always using that if direct SAN is not possible or if VBR is virtualized with iSCSI repository. It’s working stable and faster than NBD, because of the limitation in vSphere.

Does that mean that using this new feature is eliminating the speed limitation or is it only meant to isolate the traffic?

Userlevel 7
Badge +6

Hi @vNote42 , thx for sharing. I did not know it already that this is possible in vSphere right now. I always use and recommended my colleagues to use Hot-add method. I’m always using that if direct SAN is not possible or if VBR is virtualized with iSCSI repository. It’s working stable and faster than NBD, because of the limitation in vSphere.

Does that mean that using this new feature is eliminating the speed limitation or is it only meant to isolate the traffic?

Good question Nico! I did not test performance with this new service tag. But I do not think it will be faster than before.

No question, direct and hotadd mode are quite faster. But NBD is the simplest to implement. For many VMs NBD is just fast enough. So I know quite some environments where larger VMs get backed up by using direct mode and a bunch of smaller and small ones with NBD mode. For the backup windows it is fast enough with no additional components (virtual proxies) needed. And NBD scales not that bad when VMs to backup are spread across more hosts. 

Userlevel 7
Badge +6

Mhh…. the management traffic is routed over the management network, but the data traffic is routed reliable over the backup network.

And do I really want to use NBD only? We have a difference of at least one to five  - in some environments of one to ten - in speed between NBD and hotadd mode…

 

Interesting topic to discuss with all the architects here I think 😎

Interesting, joe! In my testing I did not manage to use another network for backup with preferred networks. Could it be, you use a different name resolution in your backup environment? 

Userlevel 7
Badge +6

[update]

Just updated the post: Do not use this feature, if you have to route isolated backup traffic. Some strange things happens than!

 

Userlevel 7
Badge +5

Thanks for the update. Interesting to see this one.

Userlevel 7
Badge +3

Thx for letting us know that it’s not recommended to use when isolating the backup traffic @vNote42 .

Comment