I got the same error and this is what I did to solve the problem.
- First make sure you have the latest firmware for your ReadyNAS. My version is 4.1.4
- Login to your ReadyNAS and check if the NFS protocol is enabled Under Services - Standard File Protocols
- Create a New Share and Edit the share properties for NFS. The Root privilege-enabled hosts - enter the IP of the Kernel of the ESX server
- To verify the ESX server can see this share issue this command on the ESX command line showmount -e "ipaddressof readynas box". The shares should be listed.
- If the share is listed, go to the Add Storage on the ESX server and choose NFS option. Enter the IP address of the ReadyNAS box and for the folder enter /sharename (remember the /) and give a name for the data store.
Now this should work. Leave your comments below.