I had this problem on my server (10.04 LTS) and now after upgrading (12.04 LTS), with 12.04 as clients. I mount directories via NFS4, and while reading files is no problem and has almost the same speed as ssh/scp and cifs, writing to the NFS-directory is troublesome:
- It stars out with great speed (faster-than-network), but then goes to "normal" speed. After some seconds, it halts completely (0kbps).
- While this hangs, Firefox, Thunderbird and other programs is none-responsive. However, existing terminals (Gnome terminal) works without problems, also the ones logged on the NFS-server.
- Network connection to the NFS-server is not lost, a continuous ping is acting normal, good responsetimes and no packet-loss.
- After about 30-60 seconds of hang, the write-speed normalizes, Firefox and Thunderbird is responsive, and everything is fine... for about 30 seconds. Then a new hang, and so on...
While this hang is happening, the load on the client goes up, but the server has no problems at all (as far as I can tell). I have tested this on two different clients, wireless and wired connections, and a various of network-speeds. No differences, except the length of hangs.
However, trying to copy files via CIFS, ssh (scp) and/or netcat does not have this problem. The transfer-rate is a bit higher than with NFS, but that does not bother me. But that a NFS write makes my client just hang and become totally unresponsive is a major problem!
(I have tried both async and sync - No difference)
/opt/exports/nfs 192.168.10.10/32(rw,fsid=0,no_root_squash,insecure,no_subtree_check) 192.168.10.14/32(rw,fsid=0,no_root_squash,insecure,no_subtree_check)
/opt/exports/nfs/home 192.168.10.10/32(rw,no_root_squash,insecure,no_subtree_check,sync) 192.168.10.14/32(rw,no_root_squash,insecure,no_subtree_check,sync)
/opt/exports/nfs/public 192.168.10.10/32(rw,all_squash,insecure,subtree_check,sync,anonuid=150,anongid=100) 192.168.10.14/32(rw,all_squash,insecure,subtree_check,sync,anonuid=150,anongid=100)
Does anyone know what the problem can be? Or any ideas how to debug?