I have a customer who is aking if this warning from netdiag is important from a performance standpoint. They indicate (see below) that their clients have receive window setting set above the 32768 value anyway.
Here is just one expample but this is occuring on many filers across many Data ONTAP versions and across many clients:
==== excerpted from netdiag ====
The TCP receive window advertised by NFS client ausomxfza01-nfs. is 25216.
This is less than the recommended value of 32768 bytes.
You should increase the TCP receive buffer size for NFS on the client.
==== Host values are ====
[root@ausomxfza01 ~]# sysctl -a |grep -i rmem
net.ipv4.udp_rmem_min = 4096
net.ipv4.tcp_rmem = 4096 87380 4194304
net.core.rmem_default = 2097152
net.core.rmem_max = 4194304
