This article will give you guidelines for troubleshooting NFS SR related issues on XenServer

Instructions

For creating or attaching an NFS Storage repository issues, check

1. If you  can see the mountpoint from the client?

 # showmount -e <server>

1. Check if the services are running on the NFS server (Only in case of NFS v3)

# rpcinfo -p < NFS SERVER IP > 

1. Try mounting the share manually

#mount  server:/export /mnt

For issues related to NFS server timing out messages in logs

     1. Check for network connectivity errors between XenServer and NFS Server

       On XenServer, check the ifconfig and ethtool -s statistics to see for any drops on the storage interface

1. Check if any firewall is blocking access to the NFS ports
2. XenServer supports both NFS v3 and V4
3. If still issues are happening, then capture network traces from XenServers Physical interface and from the NFS server and from the interconnect switch