Hi, This issue is directly related to the kernel of your Proxmox host environment. 2.6.32-20-pve and 2.6.32-22-pve does work properly with NFS workloads but newer kernels do not. This affects the NFS mounts done directly by guest OSes regardless the kernel version of the guest. We've tested with multiple 3.x kernels on guests. Currently running 2.6.32-20-pve on our hosts and there are no issues. I hope someone else has resources to investigate this issue further and dig up the root causes.