[CentOS] nfsvers and nfs-utils-1.3.0-0.48.el7

Thu Oct 12 17:42:38 UTC 2017
Johnny Hughes <johnny at centos.org>

On 10/12/2017 12:33 PM, Paul Heinlein wrote:
> We encountered a weird problem today, and I thought some of you might
> like to hear the solution.
> The underlying change was listed in the 7.4 changelog, so it's not a
> bug, but it may drive you buggy.
> The majority of our HPC cluster nodes run CentOS 7, though the exact
> patch levels vary from node to node. None is older than 7.3, but a few
> newer nodes were kickstarted right to 7.4.
> The problem was that our mounts of Isilon NFS exports were failing
> randomly among the nodes. Routing was fine. Network connectivity was fine.
> The short answer is that the default in 7.4, and I think in the
> nfs-utils-1.3.0-0.48.el7 package in particular, has changed. While NFS
> v4.0 was the default up to 7.3, the 7.4 protocols are subtly different:
> 1. Try NFS v4.1 first
> 2. Fail down to NFS v3
> 3. Fail down to NFS v2
> The problem is that our Isilon works with NFS v4.0, not 4.1, but 4.0 is
> not in the fail-down path.
> The short-term answer is to specify nfsvers=4.0 in our autofs
> configuration files, which works like a charm.
> Like I said, this was an announced change, but the implications escaped
> us until now. So this little writeup is just for the record.

You are not the first person to have this issue .. thanks for the post.

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