I can't join XSAN clients to the XSAN

i have a 10.8 XSAN MDC, volume mounts no issues.

We have two identical MacPro's running 10.8.

Things were "kind of" working a week or two ago, but the MDC was unstable so we rebuilt it. Now the clients won't join the new XSAN.

They don't even show as available to the XSAN in the add computer screen, although if I click add remote, they show up, it just fails on authentication.

If I boot to a new, fresh 10.8 install and join the Open Directory and join the XSAN, it works perfectly.

Obviously I could rebuild these workstations, but they are video production machines, and that's literally days of work...

I've deleted kerberos, deleted xsan prefs, unjoined/rejoined the open directory, nothing is working. There must be some latent setting on the workstation that is preventing me from joining the SAN. WHERE IS IT?

Any help is appreciated. In fact, if you can help me, I'll tell you how to get an iSCSI volume mounted as an XSAN volume ;-) (the genesis of this whole project).

Thanks!