Virtualization technology plays an important role in modern data center, as it creates an opportunity to improve resource utilization, reduce energy costs, and ease server management. However, virtual machine deployment issues arise when allocating virtual machines into single or multiple physical servers. In this paper, we explore the performance and scalability issues for virtual machine deployment in a virtualized data center. We first evaluate the image scalability when allocating multiple VMs per physical server using four typical servers in data center. Then we investigate how the overall efficiency will be affected when deploying M virtual machines into N physical machines with different deployment strategies. Experimental results show that: (i) There is a resource bottleneck when deploying single type virtual machine server into single physical server, except for composite workloads. (ii) More physical machines do not always benefit for some specific applications to support a fixed number of virtual machines. (iii) MPI and network communication overheads affect the deployment efficiency seriously.