Hello VickyVision, DanielOprea,
Thanks for the replies.
I'll consider splitting the number of sites of 2 vCenter instances so as to stay below the 10 vCenter limits.
About the remark that all "vCenter Servers in a Linked Mode group should be registered to the same vCenter Single Sign On server".
I'm not sure that this is still required in version 5.5. When I read about vSphere 5.5 SSO Deployment Modes (vCenter Single Sign-On Deployment Modes), I see :
Multisite vCenter Single Sign-On:
"Each site is represented by one vCenter Single Sign-On instance, with one vCenter Single Sign-On server, or a high-availability cluster. The vCenter Single Sign-On site entry point is the machine that other sites communicate with. This is the only machine that needs to be visible from the other sites."
I understand this to be contradictory with "Make sure that all vCenter Servers in a Linked Mode group are registered to the same vCenter Single Sign-On server." (Linked Mode Prerequisites for vCenter Server)
Regards,
Francis