Are you sure the service is running?

Yes, I can see in the configuration "Service is currently enabled".

If you get a shell on the nexenta, what do you see from:

netstat -an|grep 111

Here is a screenshot

Hmmm, any chance the centos box has iptables rules blocking this?

IPtables and Selinux are deactived on the client.

That is truly strange. Can you mount the share from any other hosts? From the nexenta itself?

I tried from other hosts, I have the same problem.

How should I do to try to mount the share from the nexenta itself ?

Is there any firewall in the nexenta ?

I am not aware of any firewall. From a shell on the nexenta, what do you get from:

rpcinfo -p XXX

where XXX is the real IP (not loopback)?

Here is a screenshot of the result.

Very odd indeed. Can you run a port scanner on the centos host, aimed at the nexenta?

On the nexenta box, execute showmount -e

It will show the export list