Veeam: NFC storage connection is unavailable.
Failed to create NFC download stream.

I’ll keep this post short as well.

Run replication Job… ERROR. Check error, huh haven’t this one before…

4/16/2021 11:22:16 AM :: Processing VMName Error: NFC storage connection is unavailable. Storage: [stg:datastore-3,nfchost:host-2,conn:vcenter]. Storage display name: [ESXi-Local-Datastore].
Failed to create NFC upload stream. NFC path: [nfc://conn:vCenter,nfchost:host-23982,stg:datastore-23983@VMName_replica/VMName.vmx].

To note on this, I did some changes, I changed a route between sites (as I needed to reduce a entire network from being improperly routed, but some of services still required access from the main location, thus some dedicated /32 routes were put in their place).

I had also just patched the host in question and was testing jobs after the patch. Since I wasn’t exactly sure which was the cause. I decided to do regular troubleshooting to get more details to the root cause.

I love Veeam, they got a nice KB to help with this. So I followed along, checking the main Veeam server log areas didn’t have the log file in question, so was pretty confident it was still using the proxy at the alt site.

Checking the log as mentioned by the KB, sure enough the same error line showed up which indicated it was DNS related. Checking the proxie’s DNS settings…. DOH. It was using a server within the routes I had removed, and didn’t create a dedicated /32 for, as I wasn’t expecting any systems here to need to communicate to that subnet.

Now that I know what the issue is… this feels familiar… oh yeah the Veeam Soap Fault issue I had to deal with

The funny part about this is… 1) it’s the same server/proxy 2) Again DNS related 3) Again going to stick with host file to avoid dependencies on DNS servers

In my case the error showed the ESXi server by the hostname WAS fully qualified, but access to a DNS server to resolve it was unavailable. As soon as I saw this I had two options:

  1. Create a route to allow the Proxy to reach required DNS servers (which won’t be available in a DR case) OR
  2. Just add a static record in the Proxy host file. (DNS server not required, but if hostname or IP changes needs to be adjusted manually here)

As you can see I have the exactly 2 options similar to my first post, the difference is now it was fully dependent on DNS. Since this is a self hosted instance of a Veeam proxy, there’s a good chance DNS access might not be available when time comes, so this option was chosen.

It’s important to note that when these types of choices are made it is well documented WHY they were made.

So in this case… to resolve it I added a record in the Proxy’s local host file

172.x.x.x     ESXi.domain.postfix

You may notice that the ESXi hostname is not within the initial error, it only tells your the datastore, the Veeam logs will indicate which lookup failed. More than likely the hostname look up for the ESXi host in which the VM will be created on.

I really hope this post helps someone. Honestly I just followed the Veeam KB which was a great source reference to troubleshooting the issue. Your case maybe different, depending on the root cause your resolution maybe different then what was discussed here.

Cheers stay safe everyone.