I'm trying to understand networking settings related to NFS and various buffer sizes (and there are quite a few).
I'm running wireshark and inspecting the TCP packets arriving at the NFS server. Wireshark is showing a packet size max 32626 during an extended write operation (client->server), assuming I am interpreting correctly ("bytes on the wire" which I suppose includes all network-layer headers, etc.)
The "rsize" and "wsize" NFS settings for exported storage is set to 32k on both C/S, so I figured the above results were a result of this setting. However, increasing these values does NOT increase the packet size shown by Wireshark.
So my question is, what other constraints could be in place? I've done a fair amount of research, and this is what I've come across so far. It seems to me that none of the network constraints below would limit transmission size to 32k:
From sysctl:
net.ipv4.tcp_mem = 4096 87380 4194304
net.ipv4.tcp_{r,w}mem = 4096 87380 4194304
net.core.{r,w}mem_max = 131071
net.core.rmem_default = 229376
My MTU is currently 8K