Every now and again an install on a new machine fails for me and I have to google to remember how to change the label. So this time I’m writing it down!
Docs.sun.com has some information on the differences between the two formats http://docs.sun.com/app/docs/doc/817-5093/disksconcepts-47761?l=en&a=view
But suffice to say that you cant install Solaris on an EFI disk, you need to change it to an SMI label. Thats done using ‘format -e’.
Select the label option, and then SMI Label. Once you have done that you can check the partition table as normal and your install can progress.