I increased my cluster from 16 to 20 machines. One issue which has come up is that I cannot connect more that 16 machines as NFS clients to the raspberry pi nfs server.
The nfs server machine runs the latest raspbian (stretch), with no exotic cofiguration.
I have looked through /lib/systemd/system to try find where and how the nfs daemon is started, with little success so far. The file nfs-kernel-sever.service has a shell variable $RPCNFSDARGS which I think is key, but which I cannot determine where it is assigned.
Any help to understand systemd and increase number of clients is appreciated.
PS. I want to understand a solution to this particular nfs problem, I am not looking for alternative data sharing techniques.
PPS: I have build a brand new server machine and I still have the same issue. I can't get past 15 machines
UPDATE: This issue seems to appear only in using Version 4 protocol. With version 3 there is no problem.