Proxmox Virtual Environment
Proxmox is a KVM hypervisor and Linux Containers (LXC), thinking using it replace TrueNAS. But after research, found that it can not use thin disk, this is a big issue for me to save disk space.
TrueNAS still got some better points compare with Proxmox VE, such as the storage management, TrueNAS ZFS management looks more fesible than Proxmox can do. But Proxmox has some other points, such as support multiple hosts, more complex networking, file based VM image. TrueNAS uses ZFS volume to manage VM image, which creates many snapshots, hope the TrueNAS can have lesser bugs, especially on ZFS snapshots.
In the end, I think I will still use TrueNAs, I need ZFS pool feature to avoid disk issue.