Trouble understanding snapshot replication

[icsy7867]

This is new territory for me. I apologize if these are stupid questions and for the length of the post.

I am running:
Freenas 11.1 U5
Xeon-D 1528
24GB DDR4 ECC
RaidZ2 with 6x 3TB disk
Mirror 2x 500GB SSD

I had performance issues running VMs on-top of the RaidZ2, even with async disabled and tried a SLOG. So I thought I would try out the Mirrored M.2 SSD drives. So far it is working pretty well! however I wanted to get some sort of "backup" of the SSD mirror in case both drives fail.

So I have setup a daily snapshot of the SSD Mirrors, and I believe I have successfully setup a replication to "localhost" onto tank/snapshots (RaidZ2 zvol)
However if i SSH into freenas and go to /mnt/tank/snapshots there is nothing there:


# cd /mnt/tank/snapshots
# ls -l
# total 0


So I thought it wasn't working, even those the replication task says "up to date"

However if I go into my "View Volumes" in the gui and look under tank -> tank -> snapshots
I clearly see my "oVirtSSD" using 14.5GB

So I am a bit confused. It looks like the data IS being replicated. But how do I use the data? If the drives were the fail, how would I restore this "remote snapshot" if I can't even access/see the files?

 

[Kevin Horton]

I saw a recent similar issue of apparently missing replicated data that was resolved by rebooting the server.

 

[Ericloewe]

(RaidZ2 zvol)

A zvol is a ZFS dataset that implements a virtual block device instead of a POSIX-compatible filesystem. The word you're looking for is "vdev", for virtual device. A zfs pool is backed by one or more vdevs.
tank/snapshots is a dataset.

With that out of the way, my first guess is that you have a directory with the same name that is mounted and thus hiding the dataset. You can check that you're actually receiving stuff using zfs list -r -t snapshot tank/snapshots.