problems with sec=krb5

[Rohit Kumar Mehta]

Hi guys, I am having some trouble getting nfsv4 mounts working whenever 
I use the -o sec=krb5 on the server.  Our nfs4 server is an EMC Celerra 
(5.5.24-2) and I have tried both Fedora and Ubuntu clients and 
successfully gotten sec=sys mounts working, but cannot get sec=krb5.

I have my clients kerberized so that I can run kinit, and then ssh from 
one machine to the other without typing the password. I had to create
a host/machineName at KERBEROSREALMNAME service principal in the Active 
Directory and add it to my /etc/krb5.keytab

I also created an nfs/machineName at KERBEROSREALMNAME service principal 
(using des-cbc-crc), and that made some of the errors go away, but now 
it is still complaining:

Mar 27 13:33:50 cselin12 rpc.gssd[24685]: processing client list
Mar 27 13:33:50 cselin12 rpc.gssd[24685]: handling krb5 upcall
Mar 27 13:33:50 cselin12 rpc.gssd[24685]: Using keytab file 
'/etc/krb5.keytab'
Mar 27 13:33:50 cselin12 rpc.gssd[24685]: WARNING: Failed to obtain 
machine credentials for connection to server files.ad.engr.uconn.edu
Mar 27 13:33:50 cselin12 rpc.gssd[24685]: doing error downcall
Mar 27 13:33:50 cselin12 rpc.gssd[24685]: processing client list
Mar 27 13:33:50 cselin12 rpc.gssd[21257]: processing client list
Mar 27 13:33:50 cselin12 rpc.gssd[24685]: processing client list

The EMC filer should have a kerberos principal as well:

[nasadmin at emccs bin]$ server_nfs server_2 -secnfs
server_2 :
RPCSEC_GSS server stats

Credential count: 1
   principal: nfs at filesm.ad.engr.uconn.edu

  No user authentication contexts

[nasadmin at emccs bin]$


Does anyone have any idea what is wrong or what I should be looking at?
I am grateful for any assistance!

Thanks,

Rohit