Abstract: Models and tools for facilitating database instance consolidation are described. One approach obtains standardized database instance performance data, receives instance isolation criteria which are applied to divide instances into sets, determines resource usage for each set, and assigns instance sets to target machines based on resource usage and capacity. Each instance set is associated with a virtual machine in some cases. A security isolation criterion indicates that specified instances shall not co-reside on a target machine; an organizational criterion indicates that specified instances shall be located together in a single data center; a compatibility criterion indicates that instances shall not reside in the same virtual machine, the same physical server, or the same server pool. Users iteratively reach an acceptable consolidation of instances at one or more data centers, such as an enhanced assignment of instances that is more efficient than a linear additive solution.