On Sat, 31 Aug 2019 at 22:28, John Harris <johnmh@splentity.com> wrote:
On Saturday, August 31, 2019 1:09:58 AM MST Tom H wrote:
> On Thu, Aug 29, 2019 at 5:40 AM John Harris <johnmh@splentity.com> wrote:
>
> >
> >
> > NFS over UDP is faster than NFS over TCP.
>

Until the ethernet switches get busy -- then it is common to find that
UDP packets are dropped. 
 
>
> When using nfsv3, yes. But nfsv4 is tcp-only.

nfsv4 is also slower than nfsv3, and isn't as well supported on different
systems.

These days, "different" usually means Windows.  The merits of different
nfs versions and UDP vs TCP depend on the workloads, network
usage and topologies, etc.  

nfsv3 locking uses separate processes.   A years ago my work had lots
of MacOS systems with nfsv3.  If a client crashed (or lost power) lock files
were sprinkled  thru the server filesystem, causing problems for backups and
other clients until the server was taken offline and the locks removed.   Our
workloads involved random transfers of 10-100GB data sets (numerical model
output or remote sensing data sets) combined with scheduled overnight
replication of a local data centre to a backup site.   As a result we
often had network congestion problems so UDP was not an option. 
 
My experience with nfsv4 on linux in this environment was relatively
free of problems.  

--
George N. White III