Proxmox NFS storage performance and async

[pizza]

I have a NFS server and Proxmox 4.4 node over 1Gbit LAN connection. When using async the performance is really great, but unsafe? Or what is the best practice to increase the performance against sync?

With sync:

/etc/exports:

/var/lib/vz/nfs/vm 192.168.123.0/24(rw,sync,no_subtree_check)

root@node4:~# pveperf /mnt/pve/vm1
CPU BOGOMIPS: 36271.84
REGEX/SECOND: 986006
HD SIZE: 1815.69 GB (192.168.123.50:/var/lib/vz/nfs/vm)
FSYNCS/SECOND: 29.31
DNS EXT: 16.28 ms
DNS INT: 7.56 ms



With async de performance is really faster:

/etc/exports:

/var/lib/vz/nfs/vm 192.168.123.0/24(rw,async,no_subtree_check)

root@node4:~# pveperf /mnt/pve/vm1
CPU BOGOMIPS: 36271.84
REGEX/SECOND: 1020917
HD SIZE: 1815.69 GB (192.168.123.50:/var/lib/vz/nfs/vm)
FSYNCS/SECOND: 1246.37
DNS EXT: 16.09 ms
DNS INT: 6.40 ms