The trouble with the failed sync is that (TAC tell me) the devices are on different versions. After upgrading the device that was unable to join we have discovered another issue. Anyone think of upgrading their must bear in mind that if you use VMWare you cannot dynamically increase the size of the inactive disk. This is what we've done and the device does not upgrade onto the new bigger hard drive - it simply upgrades using the previously used smaller one without giving any errors.
See this link for determining the drives and their usage -
https://arubanetworkskb.secure.force.com/pkb/articles/FAQ/Is-it-possible-to-delete-the-standby-drive-of-CPPM-after-upgrade
You can list the images on the disk using the command - system boot-image -l
and you can boot between the versions using, for example - system boot-image 6.2.0.123
TAC have also said that you must also reset the databases for the subscriber nodes which could take up to four hours for a large setup.
I wonder why none of these things are documented, if we had have known all this at the start we could have planned all this and saved ourselves a lot of hassle and loss of face with the customer. Aruba's lack of documentation bites us in the *** again.
Also does anyone know where I can download the 6.3 user guide?