[ClusterLabs] ClusterLabs] Failing over NFSv4/TCP exports

[Dan Swartzendruber]

Thanks for the info. I only use esxi, which likely explains why I never had issues...

Patrick Zwahlen <paz at navixia.com> wrote:
>Hi,
>
>> -----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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