zfs zvol performance storage

On my proxmox server, I 'zfs create -V 16G zfs/zvol', I see the device it's /dev/zd0. I cannot see this device in proxmox UI anywhere, I can't use it as a HDD for any new VM or as a extra device to any existing VMs. I can't even put LVM on top of it from the proxmox host as I get an error...

Hi, I'm evaluating Proxmox 5 on a test server and the storage performance in guest seems very poor compared to that of the host. The root cause seems the zvol performance. In the past week I've read various threads started by people with similar problems but none of their solutions worked for...