The mount arguments on the CLIENT according to /proc/mounts rootfs / rootfs rw 0 0 none /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0 none /proc proc rw,nosuid,nodev,noexec,relatime 0 0 none /dev devtmpfs rw,relatime,size=2021240k,nr_inodes=505310,mode=755 0 0 none /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0 fusectl /sys/fs/fuse/connections fusectl rw,relatime 0 0 /dev/disk/by-uuid/e21a8bd2-83f6-43ed-8c68-08fcdc85631b / ext4 rw,relatime,errors=remount-ro,barrier=1,data=ordered 0 0 none /sys/kernel/debug debugfs rw,relatime 0 0 none /sys/kernel/security securityfs rw,relatime 0 0 none /dev/shm tmpfs rw,nosuid,nodev,relatime 0 0 none /var/run tmpfs rw,nosuid,relatime,mode=755 0 0 none /var/lock tmpfs rw,nosuid,nodev,noexec,relatime 0 0 /dev/sdb5 /media/d1 ext3 rw,relatime,errors=continue,commit=5,barrier=0,data=ordered 0 0 /dev/sdb6 /media/d2 ext3 rw,relatime,errors=continue,commit=5,barrier=0,data=ordered 0 0 binfmt_misc /proc/sys/fs/binfmt_misc binfmt_misc rw,nosuid,nodev,noexec,relatime 0 0 192.168.1.103:/media/d5 /media/d5 nfs rw,sync,nosuid,nodev,noexec,noatime,nodiratime,vers=3,rsize=262144,wsize=262144,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=192.168.1.103,mountvers=3,mountport=36708,mountproto=tcp,addr=192.168.1.103 0 0 192.168.1.103:/media/d4 /media/d4 nfs rw,sync,nosuid,nodev,noexec,noatime,nodiratime,vers=3,rsize=262144,wsize=262144,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=192.168.1.103,mountvers=3,mountport=36708,mountproto=tcp,addr=192.168.1.103 0 0 192.168.1.103:/media/d3 /media/d3 nfs rw,sync,nosuid,nodev,noexec,noatime,nodiratime,vers=3,rsize=262144,wsize=262144,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=192.168.1.103,mountvers=3,mountport=36708,mountproto=tcp,addr=192.168.1.103 0 0 (Again, I tried several different settings here like UDP instead of TCP and such things.) On the SERVER we have for "apt-cache policy nfs-kernel-server" the following: nfs-kernel-server: Installiert: 1:1.2.0-4ubuntu4 Kandidat: 1:1.2.0-4ubuntu4 Versions-Tabelle: *** 1:1.2.0-4ubuntu4 0 500 http://ch.archive.ubuntu.com/ubuntu/ lucid/main Packages 100 /var/lib/dpkg/status And for "unmame -a" as stated above: Linux unimatrixserver 2.6.32-25-generic #44-Ubuntu SMP Fri Sep 17 20:05:27 UTC 2010 x86_64 GNU/Linux And for "ifconfig -a" eth0 Link encap:Ethernet Hardware Adresse 90:e6:ba:67:96:73 inet Adresse:192.168.1.103 Bcast:192.168.1.255 Maske:255.255.255.0 inet6-Adresse: fe80::92e6:baff:fe67:9673/64 Gültigkeitsbereich:Verbindung UP BROADCAST RUNNING MULTICAST MTU:1500 Metrik:1 RX packets:62655615 errors:0 dropped:0 overruns:0 frame:0 TX packets:69746827 errors:0 dropped:0 overruns:0 carrier:1 Kollisionen:0 Sendewarteschlangenlänge:1000 RX bytes:46398335710 (46.3 GB) TX bytes:84718869326 (84.7 GB) Interrupt:27 lo Link encap:Lokale Schleife inet Adresse:127.0.0.1 Maske:255.0.0.0 inet6-Adresse: ::1/128 Gültigkeitsbereich:Maschine UP LOOPBACK RUNNING MTU:16436 Metrik:1 RX packets:1490399 errors:0 dropped:0 overruns:0 frame:0 TX packets:1490399 errors:0 dropped:0 overruns:0 carrier:0 Kollisionen:0 Sendewarteschlangenlänge:0 RX bytes:1642881434 (1.6 GB) TX bytes:1642881434 (1.6 GB) (As you can see the outputs are partially in German at my machine but I think you can guess the meaning since you know how the output would look in English and since technical German and technical English are quite similar. Of course I can try to translate if needed.) Being not an expert I don't know exactly what will help you to build a solid and repeatable test case, but of course I will provide you with more details if you tell me what is needed. I also gathered those Informations: apt-cache policy nfs-common (at the SERVER) nfs-common: Installiert: 1:1.2.0-4ubuntu4 Kandidat: 1:1.2.0-4ubuntu4 Versions-Tabelle: *** 1:1.2.0-4ubuntu4 0 500 http://ch.archive.ubuntu.com/ubuntu/ lucid/main Packages 100 /var/lib/dpkg/status apt-cache policy nfs-common (at the CLIENT) nfs-common: Installiert: 1:1.2.2-1ubuntu1 Kandidat: 1:1.2.2-1ubuntu1 Versionstabelle: *** 1:1.2.2-1ubuntu1 0 500 http://ch.archive.ubuntu.com/ubuntu/ maverick/main amd64 Packages 100 /var/lib/dpkg/status 1:1.2.0-4ubuntu4 0 500 http://ch.archive.ubuntu.com/ubuntu/ lucid/main amd64 Packages 500 http://archive.ubuntu.com/ubuntu/ lucid/main amd64 Packages Two additional informations that maybe are helpful: 1. I just booted the client machine (which normally runs 10.10) with a Kubuntu 10.04 LiveCD and then mounted the nfs shares and tried to make a large file transfer. The system also crashed. Interesting is: When using the LiveCD, my 'home' folder (which must be at the RAM, I think) can hold 1,7 GB. When trying to copy a 4GB file to it, the machine did NOT crash but tell me that there is not enough space (of course) after about 40% of the transfer happened. When trying to copy the same file via the LiveCD to a real local partition (instead of the RAM-Disk), the machine crashes immediately. 2. There is discussed such an issue here: http://ubuntuforums.org/showthread.php?t=1478413&page=1 AND there seemed to exist some kernel patch which worked for some people (described on page 3 of this thread). I don't know if this helps but you may want to have a look at it.