Hi Yang,
The Cisco UCS does hardware abstraction/virtualization similar to how VMware does abstraction for the operating system from the underlying server, we do the same with the personalities that make up a server from the actual physical compute resources.
Each time you create a service profile, you are creating a logical server which has all the characteristics of a physical server (MAC address, WWPNs, WWNNs, vNICs, vHBAs, BIOS, UUID, etc). You can then associate this service profile to any physical blade and that logical server with all your predefined personalities will utilize the physical compute resources. You can move this service profile around to any blade within the UCS cluster, each time it will maintain the characteristics that you defined, no matter which physical blade it is actually using.
To answer your question, it is not possible to have 9 service profiles associated to a server pool of 8 blades and be running 9 ESXi instances. You can only run as many instances as there are physical blades. There is a one to one relationship between a service profile (once associated) and a physical blade. You can however have, for example, have 16 service profiles (logical servers) and only have 8 blades. You might have 8 service profiles associated during the day time, performing a particular task. Then at night, you need to run different workloads. So you could unassociate the original 8 service profiles, then associate the last 8 service profiles to run their workload on the physical compute resources during the night. Then switch back again in the morning. This is just an example.
Seeing that you are new to the UCS, a good place to start is with our Video Library:
http://www.cisco.com/en/US/prod/ps10265/ucs_advantage_video_library.html
Hope that helps to clarify things for you.
Thanks,
Michael
