  With the rapid development of virtualization techniques, cloud data centers
allow for cost effective, flexible, and customizable deployments of
applications on virtualized infrastructure. Virtual machine (VM) placement aims
to assign each virtual machine to a server in the cloud environment. VM
Placement is of paramount importance to the design of cloud data centers.
Typically, VM placement involves complex relations and multiple design factors
as well as local policies that govern the assignment decisions. It also
involves different constituents including cloud administrators and customers
that might have disparate preferences while opting for a placement solution.
Thus, it is often valuable to not only return an optimized solution to the VM
placement problem but also a solution that reflects the given preferences of
the constituents. In this paper, we provide a detailed review on the role of
preferences in the recent literature on VM placement. We further discuss key
challenges and identify possible research opportunities to better incorporate
preferences within the context of VM placement.
