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Subject: safe versions of NFS
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Date:   Tue, 13 Apr 2021 10:33:49 -0400
To:     linux-nfs@vger.kernel.org
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I am in charge of a large computer science dept computing infrastructure. W=
e have a variety of student and develo9pment users. If there are problems w=
e=E2=80=99ll see them.

We use an Ubuntu 20 server, with NVMe storage.

I=E2=80=99ve just had to move Centos 7 and Ubuntu 18 to use NFS 4.0. We had=
 hangs with NFS 4.1 and 4.2. Files would appear to be locked, although even=
tually the lock would time out. It=E2=80=99s too soon to be sure that movin=
g back to NFS 4.0 will fix it. Next is either NFS 3 or disabling delegation=
s on the server.

Are there known versions of NFS that are safe to use in production for vari=
ous kernel versions? The one we=E2=80=99re most interested in is Ubuntu 20,=
 which can be anything from 5.4 to 5.8.