[Gluster-users] UDP instead of TCP?

Jeff Darcy jdarcy at redhat.com
Mon Sep 23 19:41:40 UTC 2013

On 09/23/2013 03:31 PM, Paul Robert Marino wrote:
> In general link speeds are fast enough that TCP is preferred for NFS. The UDP
> transport is a vestige of running NFS over network connections that were slower
> than the disk they would read and write from nowadays the reverse is generally
> true and TCP is the safer transport method.

To be a bit more specific, on modern networks NFS over UDP is susceptible to 
fragment-ID wraparound which could lead to data corruption.  This has been well 
known since at least 2006[1].  On modern machines the difference in processing 
time between TCP and UDP is negligible, so there's just no good reason to take 
that risk.  BTW, I've been using/developing NFS since v2 in 1990, when the 
difference really might have mattered.  If I can see that NFS over UDP is past 
its sell-by date, so can anybody else.  ;)

[1] http://nfsworld.blogspot.com/2006_03_01_archive.html

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