Date: Wed, 30 Mar 2022 11:26:17 +0200 From: Andrea Venturoli <ml@netfence.it> To: freebsd-questions@freebsd.org Subject: NFS server flooded and vfs.nfsd.tcphighwater Message-ID: <604a9a83-fddf-4923-bdd9-4b845cb7be42@netfence.it>
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Hello. From time to time, on an NFS4 server of mine, I see this message: > nfsd server cache flooded, try increasing vfs.nfsd.tcphighwater It's typically when I installworld on a client (src and obj being on this server) and it's repeated over and over. Nothing nasty seems to happen (perhaps only a slowdown???) and the lack of documentation leaves me wondering what to do (if anything) with this. man page says: > If the server has stopped servicing clients and has generated a console > message like "nfsd server cache flooded...", the value for > vfs.nfsd.tcphighwater needs to be increased. This should allow the > server to again handle requests without a reboot. Also, you may want to > consider decreasing the value for vfs.nfsd.tcpcachetimeo to several > minutes (in seconds) instead of 12 hours when this occurs. Well, for a start it doesn't really look like the server stopped servicing... Then there's no indication of what value should be reasonable. In fact it's not even clear what unit we are talking about (bytes? kB? some unspecified count?). If vfs.nfsd.tcphighwater had a starting value I could think about doubling it, raising it tenfold or whatever; alas it's default value is 0. Some forums show people used some apparently random value like 300000, while admitting they had no idea what they were doing. Any pointer? bye & Thanks av.
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