This was first disabled on groovy, the first ubuntu release after focal: root@g1:~# grep NFS /boot/config-5.8.0-59-generic |grep UDP CONFIG_NFS_DISABLE_UDP_SUPPORT=y
The upstream help text next to that kernel option says: """ Choose Y here to disable the use of NFS over UDP. NFS over UDP on modern networks (1Gb+) can lead to data corruption caused by fragmentation during high loads. """ I'll leave it to the kernel team to comment further. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1964093 Title: nfsver=3,udp not working anymore Status in linux package in Ubuntu: Confirmed Bug description: Package: nfs-kernel-server Architecture: amd64 Version: 1:2.6.1-1~exp1ubuntu1 nfsversion 3 with proto udp seems not to be supported by the nfs- kernel-server anymore. In Ubuntu 18.04 (nfs-kernel-server 1:1.3.4-2.1ubuntu5) it was still possible. I could mount with either tcp or udp: 1. tcp mount -o nfsvers=3 192.168.0.1:/srv/nfs/testshare /mnt mount|grep mnt: 192.168.0.1:/srv/nfs/testshare on /mnt type nfs (rw,relatime,vers=3,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=192.168.0.1,mountvers=3,mountport=59808,mountproto=udp,local_lock=none,addr=192.168.0.1) 2. udp mount -o nfsvers=3,udp 192.168.0.1:/srv/nfs/testshare /mnt mount|grep mnt: 192.168.0.1:/srv/nfs/testshare on /mnt type nfs (rw,relatime,vers=3,rsize=32768,wsize=32768,namlen=255,hard,proto=udp,timeo=11,retrans=3,sec=sys,mountaddr=192.168.0.1,mountvers=3,mountport=59808,mountproto=udp,local_lock=none,addr=192.168.0.1) Now in Ubuntu 22.04 I get the message: mount.nfs: an incorrect mount option was specified I tried to enable upd in /etc/nfs.conf in section [nfsd]: [nfsd] # debug=0 # threads=8 # host= # port=0 # grace-time=90 # lease-time=90 # udp=n udp=y # tcp=y # vers2=n # vers3=y But there was no effect. nfs3 with udp is needed by several busybox mount binaries in initrds of Knoppix and other live distributions used via PXE boot. Best regards Jörg To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1964093/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp