Backup controllers are mounted but Admin says Unreachable!

Hi,

I have just finished upgrading our complete system. Everything has had a clean install, Raids reformatted, Fibre switch reset, cables were left alone as the old Xsan was working fine ie everything was talking.

Having setup the Xsan2 on the main controller all seamed fine, every client and controller has mounted the volumes permissions all set etc.

Now... in Xsan Admin the two backup controllers now say they are unreachable but still mounted, I can not make if failover, whereas 10mins earlier I could.

Any ideas.... Apple support not much help so far.