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From:   "Benjamin Coddington" <bcodding@redhat.com>
To:     hedrick@rutgers.edu
Cc:     "Patrick Goetz" <pgoetz@math.utexas.edu>, linux-nfs@vger.kernel.org
Subject: Re: safe versions of NFS
Date:   Tue, 13 Apr 2021 11:35:50 -0400
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It would be interesting to know why your clients are failing to reclaim 
their locks.  Something is misconfigured.  What server are you using, 
and is there anything fancy on the server-side (like HA)?  Is it 
possible that you have clients with the same nfs4_unique_id?

Ben

On 13 Apr 2021, at 11:17, hedrick@rutgers.edu wrote:

> many, though not all, of the problems are “lock reclaim failed”.
>
>> On Apr 13, 2021, at 10:52 AM, Patrick Goetz <pgoetz@math.utexas.edu> 
>> wrote:
>>
>> 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.