*SOLUTION*: Ok so I found the problem. Below is my original post and the symptoms as I saw them at the time. The solution was to add the host in CPP's UI and the host was suddenly able to connect to the storage. To me it seems to make more sense to get all your networking/SRs in order before adding to the cluster but no more than 2 seconds after the host was added the shared SRs were all healthy again (i.e.: all hosts are connected to them) so there's no doubt i my mind this is what made the difference.

Edit: FYI, This is a XenServer which is part of a CloudPlatform Cluster
Edit2: Same issue as http://forums.citrix.com/thread.jspa?threadID=266876&tstart=0 which went unanswered

I've joined a new slave to an existing pool of XenServers but unable to get it to connect to the Primary storage. Here's what I did:

1. Fresh install of XenServer
2. Join to the XenServer pool
3. Verify the management interfaces, make sure they match (in my case, I needed to define the storage network as well as add DNS server for the Primary interface)

Once I was done the above and I've verified that my network settings are correct, I attempted to repair the broken connection to the SR however it fails with "Internal error: Failure("Storage_Access failed with: SR_BACKEND_FAILURE_73: NFS mount error opterr=mount failed with return code 32

I've confirmed I can mount the NFS export from the XenServer without any problems but when I tell XenCenter to repair the SR it fails. Any hints/tips/tricks/direction would be much appreciated.