Storage does not allow other than disk image & container on ZFS pool?

[Deleted member 205422]

In the Datacentre settings, specifically Storage, it is impossible to select e.g. ISOs, templates, backups, etc. for a ZFS pool. Why?

I understand that it is possibly a workaround to add a Dir being a ZFS dataset, but why not allowing selecting the actual pool?

Does this have anything to do with how PVE handles ZFS pools across nodes or some historical reasons?

 

[leesteken]

In the Datacentre settings, specifically Storage, it is impossible to select e.g. ISOs, templates, backups, etc. for a ZFS pool. Why?

You cannot store files on a pool without first creating a filesystem (zfs create) on it, which you add as a Directory Storage in Proxmox.
ZFS pools can contain zvols (virtual disks) and subvols (filesystems, which can contain files) but not files; it's just the nature of ZFS.

 

[Deleted member 205422]

Thanks, I am familiar with ZFS intricacies, but PVE behaves differently when ZFS is used as backend for VMs/CTs and I struggle to understand why.

For instance, it would be logical for nodes that are in a cluster to base LXC container on "template" as ZFS datasets can refer to underlying datasets. Given the replication and migration capabilities it would only make sense to provision such a template on all (where a child VM/CT it is being replicated) nodes in the cluster. In which case one would not need to manually create a ZFS dataset to store ISOs, templates, etc. This would be expected behaviour.

But this is not how it works, the template is stored locally (to the node only) or shared (via networked filesystem) or possibly on CEPH volume (but that's out of scope for this query), then CT is created, if one sets replication across 2 nodes for, let's say 10 CTs based on the same template, they all take space multiple times (no I do not want to use deduplication) because the other node can't have the underlying dataset in its pool.

How was this meant to work when created? Will I avoid this issue if choose e.g. BTRFS instead of ZFS?