[ClusterLabs] Failing over NFSv4/TCP exports

Patrick Zwahlen paz at navixia.com
Thu Aug 18 08:09:23 EDT 2016


> -----Original Message-----
> From: Andreas Kurz [mailto:andreas.kurz at gmail.com]
> Sent: mercredi, 17 août 2016 23:16
> To: Cluster Labs - All topics related to open-source clustering welcomed
> <users at clusterlabs.org>
> Subject: Re: [ClusterLabs] Failing over NFSv4/TCP exports
> This is a known problem ... have a look into the portblock RA - it has
> the feature to send out TCP tickle ACKs to reset such hanging sessions.
> So you can configure a portblock resource that blocks the tcp port
> before starting the VIP and another portblock resource that unblocks the
> port afterwards and sends out that tickle ACKs.

Thanks Andreas for pointing me to the portblock RA. I wasn't aware of it and will read/test.

I also made some further testing using ESXi and I found out that the ESXi NFS client behaves in a completely different way when compared to the Linux client and at first sight it actually seems to work (where the Linux client fails).

It's mainly due to 2 things:

1) Their NFS client is much more aggressive in terms of monitoring the server and restarting sessions.

2) Every new TCP session comes from a different source port compared to the Linux client which seems to stick to a single source port. This actually solves the issue of failing back to a node with FIN_WAIT1 sessions.

Regards, Patrick

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