Hello everyone
My single 4TB HDD is slowly filling up and I want to replace it. This HDD holds the snapshots only, even if I lose the content, it’s not a big deal because I replicate everything on another box.
With that said, I have 10+ snapshots tasks configured, and I would like to not reconfigure them after the disk replacement.
Is it possible? If yes, what’s the best approach?
Thank you very much!
Do you have a spare SATA / SAS Port?
Yep I do
Then get a bigger disk, mirror the existing one (turn it into a mirror vdev). Once the re-silver is complete then simply remove the original disk from the mirror and turn it back into a stripe of 1 disk.
You may need to click a button to add the extra space once the process is complete
What exactly do you mean by that?
That HDD is configured to store the Snapshots of the primary array where all my data is
Okay, I’d probably call this backup or, probably more fitting as some people are very… intense about the term backup: replica.
Well, as a matter of fact… on the truenas GUI it stays snapshot 
I think you’re mixing stuff up. There are snapshot tasks, they automatically create snapshots which preserve the state of a dataset (and optionally it’s children) within a pool. You cannot create a snapshot of a dataset on another dataset.
Then there are replication tasks which replicate one dataset (and optionally it’s children) onto another which may be on another pool or system and use snapshots for increments.
If you say you have a dedicated HDD for snapshot…that just doesn’t make sense.
You may have a dedicated pool on a single disk and replicate datasets from another pool to this one or you may have a pool and create snapshots on it but that would not involve a dedicated “snapshot disk”.
Posting screenshots of your set up and explaining it may help our understanding and what features you are using
Probably better if you post screenshots from a regular PC. You are showing you have Periodic Snapshots set up but we really can’t make out the detailed pool info nor work out why or how you are storing the snapshots. Maybe detailed hardware and how your pools are set up would help.
I was attempting to clear up any mix up or translation errors.
@SmallBarky is absolutely correct. It would be best if you could give us a full screenshot of the data protection page, maybe the pools and/or datasets page and some hw details.
So far it looks like you have a RAIDZ2 consisting of SSDs?
No hint of an HDD here yet though.
Okay so it’s basically this. You have Snapshot tasks on the SSD pool which create snapshots on this pool and then you replicate datasets from the SSD pool (using snapshots) to the single-HDD pool which therefore holds replicas of the SSD-pool datasets.
I don’t really get the use case for the HDD though - the SSD pool already has 2 disks of redundancy and you said earlier you also replicate to another system. Why replicate anything to a local HDD?
The screenshot of the Replication Tasks does not show if all replication tasks go to the HDD or if some are to the other system you mentioned but … I still don’t get why the HDD is even there.
You are correct, sorry for the confusion.
The snapshots are there to restore any deleted files (I mainly use Immich on my TrueNAS), and as a redundancy, I copy those snapshots to the local HDD, in case I need to restore the snapshots or recovery from them, the local HDD will be much faster compared to the other system which is in another location and reachable via S2S VPN.
Does that mean you have a differnt snapshot retention policy on the HDD pool than on the SSD pool?
Otherwise the snapshots are also on the SSD pool which will be much faster to restore than from the other local pool.
Yes, I can’t remember exactly but on the HDD is surely at least 1 year, much more than the SSD
Okay, now I finally get what the purpose of that HDD is - it’s still smaller than the SSD pool so I suspect you only keep certain data from that on there for longer but I’m now happy that this all makes sense 
FYI I didn’t even have to create a raid 1 (mirror). Truenas offered me to replace that disk. After resilvering, everything went back to normal.
Thank you all for the help 
