SMB Multichannel transport for On-Host Backup

[l4k3k3m4n]

Hello,
I am currently investigation this scenario:

-Hyper-V host with VMs on local storage.
This host has a NIC team (1G) for management stuff and additional standalone NICs for storage (10G SMB3).

Same configuration on the veeam backup server, which holds the local backup repository.

So is it possible for veeam to use SMB3 multichannel during the on-host backup process to transfer the backups from the hyper-v host to the veeam server/repository?

I tested a bit, but veeam seems to use only the primary NIC (which is the 1G team).
A typical windows file transfer between host and backup server uses the 10G NICs (SMB3 multichannel) automatically.

Thanks for your help.

[Mike Resseler]

Hi Moritz,

Did you configured the preferred networks? See here for more information: https://helpcenter.veeam.com/docs/backu ... tml?ver=95

[l4k3k3m4n]

Hello Mike,

you are right, I can configure the preferred network to directly use a single of the 10G NICs.

But still it is not using SMB3 multichannel, which would (automatically) detect and use all available NICs and spread the load on them.
Is this not possible?

Thanks

[Mike Resseler]

Hi Moritz,

Sorry for the late reply but I had to ask some Windows Server 2016 networking experts for some guidance.

1. I assume that your 2 NICs for multichannel are on the same subnet?
2. Did you change SMB constraints?
3. There are cases (not documented by MSFT but seen in the field quite a few times) that you need to reboot host(s) / veeam server after changing the settings on those NICs. Apparently it is a best practice to do when working with SMB 3 and the new features

Let me know

Mike

[l4k3k3m4n]

Hello Mike,

yes the 10G NICs for SMB3 are in the same subnet.
I did not change any SMB constraints.
Yes the servers were rebooted quite a few times.

Generally multichannel is working fine.

When I do a file copy from hyper-v host to veeam server (or the other way) the transfer will use both 10g NICs on both servers.

When I run a veeam backup between the same servers it will use the primary 1G nic teams.
When i configure the preferred network in veeam It will use 1 of the 10g NICs in both servers.

So it seems veeam never triggers a SMB3 multichannel connection for the backup transfer.

Thanks.

[Mike Resseler]

Moritz,

I'm out of ideas. I have seen this working with Hyper-V 2016 SMB3 MC and B&R server (also a 2016) with SMB 3 MC enabled.

Maybe you can contact support about this. It might be that they see something in the logs that explains why only 1 channel is being used at your side

Sorry

[SBarrett847]

I'm seeing this with a new SMB based Repo I've just deployed, did support give any hints as to where to look?

[foggy]

Hi Stephen, no case ID here to check, so I recommend contacting support directly to open your own case for investigation.

[SBarrett847]

Turns out it very likely I've set the wrong Repository Gateway for the repository for SMB multichannel to operate. I've have had to set the SMB based repo as its own gateway (It's on Server 2019), because the Backup Server is only 2012 and can't act properly as a gateway for an ReFS repo.

It was explained to me, that were I to set the Backup server as the gateway to the new repo, SMB multi-channel would work fine. I plan to upgrade the backup server to at least 2016 in the new year, and I'll re-check then.