Patent attributes
Placement of virtual machines on physical hosts is based on a preferred host list that may be generated from preferred host identifiers to more efficiently utilize system resources and serve the needs of different workloads. A host identifiers mechanism allows a system administrator to select preferred host identifiers for each virtual machine or a group of virtual machines. The host identifiers mechanism in conjunction with an optimizer periodically adjusts the placement of virtual machines according to the preferred host identifiers and consistent with optimization policies. Further, the preferred host identifiers may include a time component so that the preferred host resources can be periodically updated and can dynamically change over time.