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Subject: Re: safe versions of NFS
To:     hedrick@rutgers.edu, linux-nfs@vger.kernel.org
References: <D8F59140-83D4-49F8-A858-D163910F0CA1@rutgers.edu>
From:   Patrick Goetz <pgoetz@math.utexas.edu>
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Date:   Tue, 13 Apr 2021 09:52:52 -0500
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I use NFS 4.2 with Ubuntu 18/20 workstations and Ubuntu 18/20 servers 
and haven't had any problems.

Check your configuration files; the last time I experienced something 
like this it's because I inadvertently used the same fsid on two 
different exports. Also recommend exporting top level directories only. 
  Bind mount everything you want to export into /srv/nfs and only export 
those directories. According to Bruce F. this doesn't buy you any 
security (I still don't understand why), but it makes for a cleaner 
system configuration.

On 4/13/21 9:33 AM, hedrick@rutgers.edu wrote:
> I am in charge of a large computer science dept computing infrastructure. We have a variety of student and develo9pment users. If there are problems we’ll see them.
> 
> We use an Ubuntu 20 server, with NVMe storage.
> 
> I’ve 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 eventually the lock would time out. It’s too soon to be sure that moving back to NFS 4.0 will fix it. Next is either NFS 3 or disabling delegations on the server.
> 
> Are there known versions of NFS that are safe to use in production for various kernel versions? The one we’re most interested in is Ubuntu 20, which can be anything from 5.4 to 5.8.
> 
>