I'm having the same problem. Deploying a second vCenter appliance at a second site and I have exactly the same message. I thought maybe it had to do with the latest build, but have tried 4 different builds with no success. I'm also running 5.1. Desperately need to get this working, so any help would be appreciated.
One question for those who are also having this issue, are you running ESXi on supported hardware? I'm running on supported Dell servers, but a third party RAID controller in the servers at the second site. It recognizes the array and allows creation of a data store. The hosts boot and run Windows VMs with no problem, and will write to the VMDK from within Windows. It seems as though the virtual vCenter appliance VMDK file is read only. I can't write any files from within the command line and get "Segmentation fault (core dumped)" when running vpxd commands.