Trying to backup to external USB drive via Replication

(Reposted from the TrueNAS subreddit)

I am currently running a 12TB TrueNAS system, primarily as a media server but also to back up other systems in the house. I found a good deal on a 14TB external USB drive, so I decided a proper backup for the NAS was a good idea. I set it up according to recommendations in this thread: Reddit - Dive into anything (specifically the recommendation by konzty to use a single-disc pool on the backup drive, and then use Replication to regularly snapshot the changes and copy to the backup. Everything seems to be working, I get notifications that the replication tasks have succeeded, etc. However…

My dashboard for the backup pool says that there are over 12 TB free, and I’ve effectively used 0% of available space. That definitely doesn’t seem right! If I go look at pools, for instance, it shows similar info. Any ideas? Is TrueNAS somehow not reporting the state of the backup drive correctly? Seems more likely that I’ve set up something incorrectly and it never copied the initial image, but it seems relatively simple and I’m not sure what I could have done wrong (I am in no way an expert on this stuff however!).

I’m not even sure how to check the content on the backup drive outsid3e of TrueNAS, since I don’t think any of my other machines can understand a ZFS disk.

Any advice appreciated!

You probably replicated the top-level root dataset, without invoking “recursive” or “full filesystem backup” in the Replication Task’s options.

Without seeing any more information, we can only speculate…

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I think you can share on SMB (or similar) the backup pool

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Output from this command can be helpful;
zpool list
Please post the output in CODE tags.

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So the zpool list shows all space free on the backup drive. But I think the suggestion above that neither Recursive nor Full Filesystem Backup were checked is correct, I just checked my task and indeed they are both unchecked.

Full Filesystem Backup seems pretty obvious, but I’m not clear about the Recursive. Is that something that I should check for a backup replication task?

“Recursive” will include all child datasets that live underneath the selected source dataset. (Since you chose the root dataset as the “source”, you basically selected an empty “placeholder” dataset. Your data lives on children dataset.)

“Full Filesystem Replication” implies recursive (above) + all properties, volumes, and clones.

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OK, sorry for the newb questions…I checked the full file system replication and re-ran it, and quickly go the following error notification (Note: “deadpool” is the main data pool I’m trying to back up):

Replication “deadpool - NAS Backup Pool” failed: skipping snapshot deadpool@auto-2024-06-04_00-00 because it was created after the destination snapshot (auto-2024-06-03_00-00) skipping snapshot deadpool@auto-2024-06-05_00-00 because it was created after the destination snapshot (auto-2024-06-03_00-00) cannot send deadpool@auto-2024-06-03_00-00 recursively: snapshot deadpool/iocage@auto-2024-06-03_00-00 does not exist warning: cannot send ‘deadpool@auto-2024-06-03_00-00’: backup failed cannot receive: failed to read from stream…

2024-06-05 12:16:59 AM (America/New_York)

I have had some problem after editing an existing task… I dont know if exist a better way but i just

  • delete task
  • delete snapshot
    And create new task from scratch
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