[Linux-cluster] slow NFS performance on GFS2

[Olivier Desport]

Hello,

I've installed a two nodes GFS2 cluster on Debian 7. The nodes are 
connected to the datas by iSCSI and multipathing with a 10 Gb/s link. I 
can write a 1g file with dd at 500 Mbytes/s. I export with NFS (on a 10 
Gb/s network) and I only can reach  220 Mbytes/s. I think that it's a 
little bit far from 500 Mbytes/s...

Do you how to tune my settings to increase the speed for NFS ?

GFS2 mount :
/dev/vg-bigfiles/lv-bigfiles /export/bigfiles gfs2 
_netdev,nodiratime,noatime 0 0

NFS export :
/export/bigfiles 
172.16.0.0/16(fsid=2,rw,async,no_root_squash,no_subtree_check)

mount on NFS clients :
nfs-server:/export/bigfiles /data/bigfiles nfs4 
_netdev,rw,user,nodiratime,noatime,intr 0 0