Right before the timeout, the following entry appears in /var/log/messages:
The client ("cdr") is running kernel-2.6.18-406.el5. Here is the fstab entry:cdr kernel: nfs: server 172.16.0.4 not responding, still trying
The server ("depot") is running kernel 2.6.32-573.3.1.el6.x86_64. Here is the corresponding entry in /etc/exports:172.16.0.4:/export/vol2/replicated/cdr/replicated /nfs/backup nfs rsize=32768,wsize=32768 0 0
I have performed a packet capture of NFS traffic on the server side, and around 25-50% of packets appear in Wireshark as 'TCP Retransmission' and 'TCP Spurious Retransmission'. I can provide the pcap file if needed./export/vol2/replicated/cdr/replicated 172.16.6.11(rw,no_root_squash,async)