[PVE-User] Some thought about zfs based configurations

Dietmar Maurer dietmar at proxmox.com
Fri Jul 31 17:43:28 CEST 2015

> Part one: Storing CTs and VM disk images and backups.
> In general, when we create a new VM/CT, pve creates its directory structure
> and put some files under that directory. VM uses different file formats, CT
> uses directly that directory and put its files under that. LXC will use a file
> for storing its files.
> In ZFS, it is possible to create independent filesystems for all VMs and CTs,
> instead of using a top-level filesystem and put every VMs/CTs under that. To
> achieve this, it would be necessary to rewrite the storage subsystem to handle
> the zfs case.

No - Proxmox VE is already able to create and use ZFS subvolumes.

> Part three: Containers with direct access to the files from the hardware node
> (not virtual disk)
> I like the openvz approach, where the whole system is inside a directory, so,
> the CT uses directly the filesystem of the hardware node. In this case, there
> are no overhead or filesystem corruption risk, due to that, the CT uses ZFS
> "directly". Of course, on application level, for example mysql inconsistent
> situation can happen on crash or snapshot (anyway, I did never experience
> this).
> So, using ZFS with CT like this is a very good combination: individual files
> easily accessible from hardware nodes, even from snapshots without any magic
> trick: quick and elegant. And a plus, we have all zfs benefits without hacking
> the CT.

Dont really got this one (same as part one)?

> Using filesystem on lxc containers not an user choice, but choosed by the
> system developer, in this case Proxmox team.
> I would like to recommend to consider using btrfs instead of ext4 on lxc
> containers. I think, this choice is better in any case, even the underlaying
> filesystem is not zfs.

We can make that configurable - should be easy to implement.

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