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. Howeverā€¦

My dashboard for the backup pool says that there are over 12 TB free, and Iā€™ve effectively used 0% of available space. That definitely doesnā€™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 Iā€™ve set up something incorrectly and it never copied the initial image, but it seems relatively simple and Iā€™m not sure what I could have done wrong (I am in no way an expert on this stuff however!).

Iā€™m not even sure how to check the content on the backup drive outsid3e of TrueNAS, since I donā€™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 ā€œrecursiveā€ or ā€œfull filesystem backupā€ in the Replication Taskā€™s options.

Without seeing any more information, we can only speculateā€¦

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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 Iā€™m not clear about the Recursive. Is that something that I should check for a backup replication task?

ā€œRecursiveā€ will include all child datasets that live underneath the selected source dataset. (Since you chose the root dataset as the ā€œsourceā€, you basically selected an empty ā€œplaceholderā€ dataset. Your data lives on children dataset.)

ā€œFull Filesystem Replicationā€ implies recursive (above) + all properties, volumes, and clones.

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OK, sorry for the newb questionsā€¦I checked the full file system replication and re-ran it, and quickly go the following error notification (Note: ā€œdeadpoolā€ is the main data pool Iā€™m trying to back up):

Replication ā€œdeadpool - NAS Backup Poolā€ 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 ā€˜deadpool@auto-2024-06-03_00-00ā€™: backup failed cannot receive: failed to read from streamā€¦

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

I have had some problem after editing an existing taskā€¦ 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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Update: I recreated the whole thing over and itā€™s definitely creating snapshots every day like I scheduled, and the disk is now showing like 70% full, which is what I would expect from backing up the whole system. It is telling me that the backup pool is ā€œdegraded.ā€ Itā€™s a brand new drive so that seems odd. Not really sure what that means.

I still need to try to poke around on the backup drive and see if the files seem correct and uncorrupted.

Could you give us info about your backup poolā€™s layout? Please post the output of zpool status.

To me, it sounds like you used a VDEV type that expects multiple disks (e.g. mirror or Z-1) and is thus reported DEGRADED with a single disk.

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Just to give a (hopefully) final update on this. I added a USB 3.0 card, removed the backup pool and started it again with the USB 3.0 interface, and so far there have been no issues, no mysterious replication failures or degraded pools, and of course backups are much, much faster. Fingers crossedā€¦

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