TrueNAS over iSCSI: Snapshot Management

[Morgan Littlewood]

Rollback to last snapshot is acceptable for 99.9% of situations....

For deleting intermediate snapshots.. can this be done on TrueNAS UI or
does proxmox control this?
If done on TrueNAS, can Proxmox learn about (adjust to)  deleted snapshots?



On Mon, Oct 6, 2025 at 6:17 AM Max R. Carrara <m.carrara at proxmox.com> wrote:

> On Mon Oct 6, 2025 at 3:09 AM CEST, Lorne Guse wrote:
> > [...]
>
> Hi Lorne, hi Morgan!
>
> Sorry—only now finally got some time to look into this.
>
> Regarding multi-generational snapshot rollbacks: That is something
> that's possible actually; our `lvm-thin` storage supports that, for
> example [0]. You're probably running into the default implementation [1],
> hence the error.
>
> We don't support it for our ZFS pool storage though [2] (and thus also
> not for the ZFS over iSCSI storages), since `zfs rollback` doesn't
> support it without destroying intermediate snapshots [3].
>
> The user can still do rollbacks on older snapshots, they just have to
> delete the intermediate ones first, in this case. (So basically what
> `zfs rollback` requires one to do.)
>
> With all that being said, I agree with Morgan here; it's best to just
> let PVE manage the snapshots and whatever contents are on the volume, as
> it is a cleaner experience for the user. (Principle of least surprise
> and all that.)
>
> Hope that helps! If you need anything else, feel free to ping me! (:
>
> [0]:
> https://git.proxmox.com/?p=pve-storage.git;a=blob;f=src/PVE/Storage/LvmThinPlugin.pm;h=ccefd0eb24630a4ae5e206002760126dfce9304a;hb=refs/heads/master#l366
> [1]:
> https://git.proxmox.com/?p=pve-storage.git;a=blob;f=src/PVE/Storage/Plugin.pm;h=2291d72d929b9de83f7703aae146372e4b663860;hb=refs/heads/master#l1325
> [2]:
> https://git.proxmox.com/?p=pve-storage.git;a=blob;f=src/PVE/Storage/ZFSPoolPlugin.pm;h=3b3456b7482ad4388a757e80484412384a677da1;hb=refs/heads/master#l551
> [3]:
> https://openzfs.github.io/openzfs-docs/man/master/8/zfs-rollback.8.html
>
>