While ZFS adds some advantages, if you were going for snap shots and quick deploy with KVM your best bet was to use LVM as a raw device. A quick lvm snapshot + virt-clone + virsh start will let me have a cloned vm up within seconds.
Thats not saying ZFS doesn't add a lot (checksum backed store, heap of other features). But I would actually expect LVM to be faster, precisely because it is "crappier" (no checksumming, very basic address remapping, etc).
The real question will be support, if they can convince people that this will have enough life to build a user base large enough to support it moving forward. Especially if oracle stops publishing code under open source licenses.
The problem with LVM snapshots is that you have to manually reserve a portion of the logical volume to store them. And if you calculate your needs incorrectly, LVM runs out of space to preserve them, and they become corrupted (they are reported as "INVALID" in lvdisplay IIRC).
That's why I prefer KVM's built-in base image support (qemu-img create -b ...) to quickly provision VMs, instead of LVM. That's how I architected KVM hosts for my employer, running 100+ lightweight VMs each, with 1000+ disk images available on disk.
Thats not saying ZFS doesn't add a lot (checksum backed store, heap of other features). But I would actually expect LVM to be faster, precisely because it is "crappier" (no checksumming, very basic address remapping, etc).
The real question will be support, if they can convince people that this will have enough life to build a user base large enough to support it moving forward. Especially if oracle stops publishing code under open source licenses.