On 20/05/2023 01:23, Adrian Minta wrote:

Hi Pierre,

when we tested NFSv4 couple of years ago,  we found out that NFSv4 has a caching feature witch delegate file caching to a specific client. This was a problem with same share mounted on multiple servers. The contention will explode the load on the clients due to I/O waits and in some cases crash the dovecot servers.

We didn't use dovecot director at that time since NFSv3 was behaving more nicely and just worked on our tests.

It seem that some NFSv4 flags exists and could mitigate this behaviour making it resemble NFSv3 but we didn't test them.


 
NFSv4, a dozen front ends to an EMC backend, with v4 we added "noac lookupcache=none" in very early days - not sure if they are still needed.
 
otherwise just like when using NFSv3, no problems, and never used director. real (hardware) load balancers are actually smart and exponentially more reliable and robust than server based :)
 
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Regards,
Noel Butler

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