Hi all, while troubleshooting an odd NFS error, I discovered that apparently (if you can believe the man pages) the default protocol for nfs clients to mount from servers is now TCP. And it apparently started with SL4.7, tho I could find no mention of such a default protocol change while perusing the release notes for SL4.7. The following excerpts are from the man page for nfs(5) from a 4.6 system and then from a 4.7 system. Note the change in the default protocol. Under "Options for the nfs file system type" in the man page for nfs(5), ------------- For SL4.6 (man page comes from util-linux-2.12a-17.el4_6.1): tcp Mount the NFS filesystem using the TCP protocol instead of the default UDP protocol. Many NFS servers only support UDP. ------------- ------------- For SL4.7 (man page comes from util-linux-2.12a-20.el4): tcp Mount the NFS filesystem using the TCP protocol. This is the default. ------------- I am currently going thru and adding "udp" to all the SL4.7 clients' fstab entries so they will use UDP rather than TCP. My main question is, lacking any explicit protocol designation in the fstab, how can one tell which protocol a client is using? And lastly, why wasn't the change documented in the release notes? From what I've gleaned about the two protocols from googling, it appears that TCP has advantages on a lossy network but that's not our scenario. It also is not a stateless protocol, like UDP, so if a server crashes in the middle of a packet transmission, the client will hang and filesystems will need to be unmounted and remounted. So it would seem UDP is better, at least in our case. Thanks! - Larry -- P. Larry Nelson (217-244-9855) | Systems/Network Administrator 461 Loomis Lab | High Energy Physics Group 1110 W. Green St., Urbana, IL | Physics Dept., Univ. of Ill. MailTo:[log in to unmask] | http://www.roadkill.com/lnelson/ ------------------------------------------------------------------- "Information without accountability is just noise." - P.L. Nelson