SMB service stops when DC is offline

Hi Guys, new user here.
I have implemented in my work TrueNas, so far so good.
Joined TrueNas to our Domain, configure all the shares based on users an groups from the Domain, all work perfectly.
But I have one problem I can’t resolve.
My DC is a VM in Proxmox, so, every night I make a backup (that means the VM goes offline just for a few seconds) and exactly at that moment, the SMB daemon stops.
¿Have any of you experienced the same issue? ¿What should I do?
I would expect TrueNas to cache the credentials and keep working if the DC is offline just for a few seconds (really, is just roughly 30 sec), but aparently it’s not the case.

Many thanks

The DC provides services that are critical for the SMB server to function correctly (kerberos, DNS, etc). A properly designed environment should have multiple DCs that are always available and TrueNAS should be configured to use them. We do not cache credentials and this won’t change because we are not a domain controller.

TL;DR, you need to design things better :wink:

this is a really small office, max 3 computers at the same time. The idea of using a Domain is just to make credentials and shares easily for us, really we don’t even need a replica, because if the DC fails we can afford some minutes until the backup is restored.
¿Is there any other solution rather than just adding a redundant DC?

Take a maintenance window when doing backups.

Backups are during night, no one is working, the problem is that the service stops (so, every backup after the DC fails because de SMB that Proxmox uses now is not reachable), so in the morning I have 2 problems: Backups were not completed, and the SMB is stopped.

I assume you’re using Proxmox Backup with a Stop Mode option, honestly, in my years of working on thousands of servers, the benefits of stopping the server to take a backup (that is happening daily at night) are so slim, you might as well run in snapshot mode where the VM will stay up.

https://pve.proxmox.com/wiki/Backup_and_Restore

Worst case is, if you’re really want to leave the Proxmox back up running, have your truenas reboot before you guys start work so the service will restore it safe fully

I would also recommend you look at another backup solution if you don’t have one, offsite as well, the cost of paying for the storage/service is usually a lot cheaper than the cost of losing all your data in event of complete failure/fire/theft etc


awalkerix is correct in that without a DC, SMB will fail

I don’t know the company or how many people use the 3x computers, however, always assume zero-trust for anyone (even if you’re the owner and work with one other person who is a friend); a proper domain service should be used where possible, without caching or workarounds to avoid authentication via the DC. Multiple DCs is a good idea though.


I would never expect a storage solution to cache any credentials, to allow users to access files without constant auth. and would be turning that off if it was a feature; because caching means it’s saved somewhere in the system, which is a security issue.

Windows Server works the same for context, if you have File Server operating within Windows, and the DC server dies or turns off, any auth requests into the files will fail.

Exactly, I’m using Stop Mode, but since no one is working and nothing is happening to that DC at that time, I prefer the safer Stop option, Snapshots can happen during work hours.

In that case you are loosing ZFS cache every day, not ideal.

I already have an offsite backup. Rule of 3 !

Didn’t know that. Well, “problem” solved. I’ll keep my DC always up and perform only Snapshots followed by reboots when needed.

Thanks to all !

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